diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index af3e68b..2a798ea 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -4,5 +4,10 @@ project(Mdemory LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED True)
 
+set(
+	CMAKE_CXX_FLAGS_DEBUG 
+	"${CMAKE_CXX_FLAGS_DEBUG} -g3 -O0 -ggdb -fvar-tracking-assignments -fno-inline"
+)
+
 add_subdirectory(transpiler)
 add_subdirectory(qtapp)
diff --git a/src/include/main.h b/src/include/main.h
index a065515..e69de29 100644
--- a/src/include/main.h
+++ b/src/include/main.h
@@ -1,28 +0,0 @@
-#pragma once
-
-#include <vector>
-#include <QSettings>
-
-#include "parser.h"
-
-void update(bool isChanged = false);
-
-void saveMdem();
-
-struct MdemBuffer {
-	std::vector<Question*> questions  = std::vector<Question*>();
-	time_t                 trainedAt  = 0;
-	bool                   error      = false; 
-	bool                   isModified = false;
-};
-
-void updateMdemInfo(std::string filename = "", bool isChanged = true);
-
-extern QSettings *settings;
-
-#define SETTING_TIMEZONE       "timezone"	
-#define SETTING_CHARACTER_WRAP "characterWrap"	
-#define SETTING_NOT_REMEMBERED "notRemembered"	
-#define SETTING_HARD           "hard"	
-#define SETTING_MEDIUM         "medium"	
-#define SETTING_EASY           "easy"	
diff --git a/src/include/mdemList.h b/src/include/mdemList.h
new file mode 100644
index 0000000..783d98a
--- /dev/null
+++ b/src/include/mdemList.h
@@ -0,0 +1,58 @@
+#pragma once
+
+#include <qapplication.h>
+#include <qboxlayout.h>
+#include <qlabel.h>
+#include <qmainwindow.h>
+#include <qtoolbutton.h>
+#include <qwidget.h>
+#include <vector>
+#include <QSettings>
+
+#include "parser.h"
+
+struct MdemBuffer {
+	std::vector<Question*> questions  = std::vector<Question*>();
+	time_t                 trainedAt  = 0;
+	bool                   error      = false; 
+	bool                   isModified = false;
+};
+
+struct Mdem {
+    QWidget          wMdem;
+    QVBoxLayout      vMdem;
+    QLabel           wFrontText;
+    QWidget          wFront;
+    QHBoxLayout      hFront;
+    QWidget          wBack;
+    QVBoxLayout      hBack;
+    QToolButton      editButton;
+    QToolButton      deleteButton;
+    QToolButton      showButton;
+    int              labelCount;
+    QVector<QLabel*> backLabels;
+	Question        *question;
+};
+
+struct ErrorView {
+	QWidget     box;
+	QVBoxLayout layout;
+	QLabel      label;
+};
+
+struct Page {
+    size_t start;
+    size_t end;
+};
+
+void update(bool isChanged = false);
+void saveMdem();
+void updateMdemInfo(std::string filename = "", bool isChanged = true);
+QMainWindow *initMdemListWindow();
+
+#define SETTING_TIMEZONE       "timezone"	
+#define SETTING_CHARACTER_WRAP "characterWrap"	
+#define SETTING_NOT_REMEMBERED "notRemembered"	
+#define SETTING_HARD           "hard"	
+#define SETTING_MEDIUM         "medium"	
+#define SETTING_EASY           "easy"	
diff --git a/src/include/settings.h b/src/include/settings.h
new file mode 100644
index 0000000..df78e94
--- /dev/null
+++ b/src/include/settings.h
@@ -0,0 +1,7 @@
+#pragma once
+
+#include <qsettings.h>
+#include <qwidget.h>
+
+extern QSettings *settings;
+QWidget *initSettings();
diff --git a/src/include/trainWindow.h b/src/include/trainWindow.h
index 08e1b0a..49eb08d 100644
--- a/src/include/trainWindow.h
+++ b/src/include/trainWindow.h
@@ -3,7 +3,7 @@
 #include <QMainWindow>
 
 #include "main.h"
-#include "parser.h"
+#include "mdemList.h"
 
 extern QMainWindow *trainWindow;
 
diff --git a/src/qtapp/CMakeLists.txt b/src/qtapp/CMakeLists.txt
index ecdbcc7..4132a6b 100644
--- a/src/qtapp/CMakeLists.txt
+++ b/src/qtapp/CMakeLists.txt
@@ -19,7 +19,9 @@ include_directories(/usr/include/qt/Qsci)
 add_executable(
 	MdemoryApp
     main.cpp
+	mdemList.cpp
 	trainWindow.cpp
+	settings.cpp
 )
 
 target_link_libraries(MdemoryApp Qt5::Widgets /usr/lib/libqscintilla2_qt5.so api)
diff --git a/src/qtapp/main.cpp b/src/qtapp/main.cpp
index f721efd..d1e8dd9 100644
--- a/src/qtapp/main.cpp
+++ b/src/qtapp/main.cpp
@@ -1,1157 +1,10 @@
-#include <cstdio>
-#include <ctime>
-#include <format>
-#include <fstream>
-#include <iostream>
-#include <map>
-#include <qabstractbutton.h>
-#include <qboxlayout.h>
-#include <qcombobox.h>
-#include <qdialog.h>
-#include <qlabel.h>
-#include <qlayoutitem.h>
-#include <qmainwindow.h>
-#include <qnamespace.h>
-#include <qobjectdefs.h>
-#include <qsettings.h>
-#include <qsizepolicy.h>
-#include <qtoolbutton.h>
-#include <qwidget.h>
-#include <qwindow.h>
-#include <qwindowdefs.h>
-#include <regex>
-#include <sstream>
-#include <string>
-
-#include <Qsci/qsciscintilla.h>
-#include <Qsci/qscilexercpp.h>
 #include <QApplication>
-#include <QMainWindow>
-#include <QVBoxLayout>
-#include <QHBoxLayout>
-#include <QLabel>
-#include <QToolButton>
-#include <QFileSystemModel>
-#include <QTreeView>
-#include <QSplitter>
-#include <QVariant>
-#include <QMessageBox>
-#include <QScrollArea>
-#include <QSpacerItem>
-#include <QFile>
-#include <QTime>
-#include <QRegularExpression>
-#include <QStringList>
-#include <QListView>
-#include <QWindow>
-#include <QMenuBar>
-#include <QMenu>
-#include <QFileDialog>
-#include <qabstractitemmodel.h>
-#include <QFormLayout>
-#include <QSettings>
-#include <QLineEdit>
-#include <QComboBox>
-#include <QSpinBox>
-#include <QDoubleSpinBox>
-#include <QCheckBox>
-#include <QPushButton>
-#include <QStandardPaths>
-#include <QShortcut>
 
-#include "main.h"
-#include "api.h"
-#include "parser.h"
-#include "qscilexer.h"
-#include "trainWindow.h"
-
-#define TEXT_LG =        20
-#define ERROR_POOL_CHUNK 50
-#define DISTANCE         2
-#define PER_PAGE         8
-#define MDEM_BACKGROUND  "#F7F7F7"
-
-struct Mdem {
-    QWidget          wMdem;
-    QVBoxLayout      vMdem;
-    QLabel           wFrontText;
-    QWidget          wFront;
-    QHBoxLayout      hFront;
-    QWidget          wBack;
-    QVBoxLayout      hBack;
-    QToolButton      editButton;
-    QToolButton      deleteButton;
-    QToolButton      showButton;
-    int              labelCount;
-    QVector<QLabel*> backLabels;
-	Question        *question;
-};
-
-struct ErrorView {
-	QWidget     box;
-	QVBoxLayout layout;
-	QLabel      label;
-};
-
-struct Page {
-    int start;
-    int end;
-};
-
-// Memorybase info.
-// @Improve: set the default directory for convenience. It should be configured by user
-// or set to "".
-std::string              currentPath   = "/home/jorenchik/Code/mdemory/memorybase/";
-std::string              currentMdem   = "";
-QFileSystemModel        *model;
-QTreeView               *mdemList;
-QLabel                  *membaseLabel;
-
-std::map<std::string, MdemBuffer*>  buffers;
-MdemBuffer                         *currentMdemBuffer;
-
-// Mdem scroll list.
-QList<Mdem*>  mdems = QList<Mdem*>();
-QVBoxLayout  *hMdemScroll;
-QSpacerItem  *mdemSpacer;
-ErrorView*    errorView;
-
-// Editor
-Mdem* editMdem;
-
-// Pagination 
-int                 currentPage   = -1;
-std::vector<Page>   pages;
-QList<QToolButton*> paginationButtons;
-QToolButton*        prevButton;
-QToolButton*        firstButton;
-QToolButton*        lastButton;
-QToolButton*        nextButton; 
-QLabel*             paginationLabel;
-
-// Top layout.
-QLabel       *deckListLabel;
-QToolButton  *add;
-QToolButton  *btnSaveFile;
-QToolButton  *load;
-QToolButton  *practice;
-
-QsciScintilla *editor;
-QMainWindow* editorWindow;
-
-QSettings *settings;
-
-const std::regex lastPathElementExp = std::regex("(.+\\/)*(.+)"); 
-
-void showBacklabels(Mdem *mdem) {
-	for (int i = 0; i < mdem->backLabels.size(); ++i) {
-		if (i < mdem->labelCount) {
-			if (!mdem->backLabels[i]->isVisible()) {
-				mdem->backLabels[i]->show();
-			}
-		} else {
-			if (mdem->backLabels[i]->isVisible()) {
-				mdem->backLabels[i]->hide();
-			}
-		}
-	}
-}
-
-std::string outputMdem(std::vector<Question*> questions, time_t time = 0) {
-	std::stringstream ss;
-
-	int wrap_width = 80;
-	if (settings->contains(SETTING_CHARACTER_WRAP)) {
-		wrap_width = settings->value(SETTING_CHARACTER_WRAP).toInt();
-	}
-
-	if (time > 0) {
-		auto timezoneOffset = settings->value(SETTING_TIMEZONE).toInt();
-		/*time = time + 3600 * timezoneOffset;*/
-		std::tm* tm = std::localtime(&time);
-		char buffer[100];
-		std::strftime(buffer, sizeof(buffer), "%d.%m.%Y %H\\:%M", tm);
-		auto time = std::string(buffer);
-		ss << time << std::endl;
-	}
-
-	for (auto question: questions) {
-		ss << std::endl;
-		std::string cooldownPart;
-		if (question->Cooldown != 0) {
-			cooldownPart = std::format(" [{:.2f}]", question->Cooldown);
-		}
-		ss << wrapText(
-			std::format("-{}{} >\n",
-			cooldownPart,
-			" " + escapeText(question->QuestionText)),
-			wrap_width
-		);
-		if (MultiElementQuestion* mw = dynamic_cast<MultiElementQuestion*>(question)) {
-			for (auto choice: mw->Choices) {
-				char opener;
-				if (choice.IsCorrect) {
-					opener = '+';
-				} else {
-					opener = '-';
-				}
-				std::string orderModifier;
-				if (mw->type == MultiElementType::Order) {
-					orderModifier = "^";
-				}
-				ss << 
-					wrapText(
-						std::format(
-							"\t{}{} {}\n",
-							opener,
-							orderModifier,
-							escapeText(choice.Answer)
-						)
-					, wrap_width);
-			}
-		} else if (GroupQuestion* gq = dynamic_cast<GroupQuestion*>(question)) {
-			for (auto group: gq->Groups) {
-				ss << wrapText(
-					std::format(
-						"\t- {}:\n",
-						escapeText(group.name)
-					)
-				, wrap_width);
-				for (auto element: group.elements) {
-					ss << wrapText(
-					std::format(
-						"\t\t- {}\n",
-						escapeText(element)
-					)
-					, wrap_width);
-				}
-			}
-		}
-	}
-	return ss.str();
-}
-
-void makePages() {
-    pages.clear();
-	auto len = currentMdemBuffer->questions.size();
-	auto pageAmount = len / PER_PAGE;
-	if (len % PER_PAGE != 0) {
-		pageAmount += 1;
-	}
-	for (int i = 0; i < pageAmount; i++) {
-		auto startingIndex = PER_PAGE * i ;
-		auto amount = PER_PAGE;
-		if (i == currentMdemBuffer->questions.size() / PER_PAGE) {
-            amount = currentMdemBuffer->questions.size() % PER_PAGE;
-        }
-        pages.push_back(Page{startingIndex, startingIndex + amount});
-    }
-}
-
-void setupMdem(Mdem *mdem, Question *question) {
-	std::stringstream ss;
-	if (question->Cooldown > 0) {
-		ss << std::format("[{:.2f}] ", question->Cooldown);
-	}
-	ss << question->QuestionText;
-	mdem->wFrontText.setText(
-		QString::fromStdString(ss.str())	
-	);
-	if (MultiElementQuestion* mw = dynamic_cast<MultiElementQuestion*>(question)) {
-		auto choices = mw->Choices;
-		for (size_t k = 0; k < choices.size(); ++k) {
-			auto answer = choices[k].Answer;
-			switch (mw->type) {
-				case MultiElementType::Order:
-					answer = std::format("{}. {}", k + 1, answer); 
-					break;
-				case MultiElementType::MultiChoice:
-					if (choices[k].IsCorrect) {
-						answer = std::format("+ {}", answer); 
-					} else {
-						answer = std::format("- {}", answer); 
-					}
-					break;
-				case MultiElementType::Regular:
-					answer = std::format("- {}", answer); 
-					break;
-			} 
-			if (k < mdem->backLabels.size()) {
-				mdem->backLabels[k]->setText(QString::fromStdString(answer));
-			} else {
-				auto label = new QLabel();
-				label->setText(QString::fromStdString(answer));
-				mdem->backLabels.push_back(label);
-				mdem->wBack.layout()->addWidget(label);
-			}
-		}
-		mdem->labelCount = choices.size();
-	} else if (GroupQuestion* mw = dynamic_cast<GroupQuestion*>(question)) {
-		auto groups = mw->Groups;
-		std::vector<std::string> elements;
-		for (size_t k = 0; k < groups.size(); ++k) {
-			auto answer = groups[k].name;
-			elements.push_back(std::format("- {}:", answer)); 
-			for (size_t l = 0; l < groups[k].elements.size(); ++l) {
-				elements.push_back(std::format("    - {}", groups[k].elements[l])); 
-			}
-		}
-		for (size_t k = 0; k < elements.size(); ++k) {
-			if (k < mdem->backLabels.size()) {
-				mdem->backLabels[k]->setText(QString::fromStdString(elements[k]));
-			} else {
-				auto label = new QLabel();
-				label->setText(QString::fromStdString(elements[k]));
-				mdem->backLabels.push_back(label);
-				mdem->wBack.layout()->addWidget(label);
-			}
-		}
-		mdem->labelCount = elements.size();
-	}
-}
-
-void SwitchPage(int pageIdx);
-
-std::string getFilename(std::string path) {
-	std::smatch matches;
-	auto filenameMatched = std::regex_search(path, matches, lastPathElementExp); 
-	return matches[2].str();
-}
-
-void updateMdemInfo(std::string filename, bool isChanged) {
-	currentMdemBuffer->isModified = isChanged;
-	if (filename.length() > 0) {
-		std::stringstream ss;
-		ss << std::format("mdem: {}", filename); 
-		if (isChanged) {
-			ss << "*";
-		}
-		if (currentMdemBuffer->trainedAt > 0) {
-			std::tm* tm = std::localtime(&currentMdemBuffer->trainedAt);
-			char buffer[100];
-			std::strftime(buffer, sizeof(buffer), "%d.%m.%Y %H:%M", tm);
-			ss << std::endl << "Last practiced: " << std::string(buffer);
-		}
-		deckListLabel->setText(QString::fromStdString(ss.str()));
-	} else {
-		deckListLabel->setText("");
-	}
-}
-
-Mdem* makeMdem() {
-	auto mdem = new Mdem;
-	mdem->wMdem.setLayout(&mdem->vMdem);
-	
-	QString id = QString("mdem_%1").arg(1);
-	mdem->wMdem.setObjectName(id);
-
-	// Front
-	mdem->wFront.setMinimumHeight(60);
-	mdem->wFront.setLayout(&mdem->hFront);
-	mdem->wFront.setProperty("first", "true");
-	mdem->wMdem.setStyleSheet(QString(
-		"QWidget#%1 > QWidget {"
-			"border-right:  1px solid gray;"
-			"border-bottom: 1px solid gray;"
-			"border-left:   1px solid gray;"
-			"background: %2;"
-		"} "
-		"QWidget#%1 > QWidget[first=\"true\"] {"
-			"border-top: 1px solid gray;"
-		"}"
-	).arg(id, MDEM_BACKGROUND));
-
-	// Add Front Content
-	mdem->hFront.addWidget(&mdem->wFrontText);
-	mdem->hFront.addStretch(1);
-
-	mdem->editButton.setText("Edit");
-	QObject::connect(
-		&mdem->editButton,
-		&QToolButton::clicked,
-		[mdem](bool checked) {
-			editMdem = mdem;
-			if (mdem->question) {
-				editor->setText(
-					QString::fromStdString(
-						outputMdem(std::vector<Question*>{mdem->question})
-					)
-				);
-				editorWindow->show();
-				editor->setCursorPosition(1, 2);
-			}
-		}
-	);
-	mdem->hFront.addWidget(&mdem->editButton);
-
-	mdem->deleteButton.setText("Delete");
-	QObject::connect(
-		&mdem->deleteButton,
-		&QToolButton::clicked,
-		[mdem](bool checked) {
-			if (mdem->question) {
-				Question* deleted = nullptr;
-				for (int i = 0; i < currentMdemBuffer->questions.size(); ++i) {
-					if (currentMdemBuffer->questions[i] == mdem->question) {
-						currentMdemBuffer->questions.erase(currentMdemBuffer->questions.begin() + i);
-						delete mdem->question;
-						mdem->question = nullptr;
-						updateMdemInfo(getFilename(currentMdem), true);
-						break;
-					}
-				}
-				makePages();
-				SwitchPage(currentPage);
-			}
-			if (editMdem == mdem) {
-				editorWindow->hide();
-			}
-		}
-	);
-	mdem->hFront.addWidget(&mdem->deleteButton);
-	
-	mdem->showButton.setText("Show");
-	mdem->hFront.addWidget(&mdem->showButton);
-
-	// Back
-	QVBoxLayout *hBack = new QVBoxLayout();
-	mdem->wBack.setLayout(&mdem->hBack);
-	mdem->vMdem.addWidget(&mdem->wBack);
-
-	// Add Back Content
-	for (int i = 0; i < 20; ++i) {
-		// @Improve: back label pooling
-		QLabel *elBackText = new QLabel();
-		mdem->hBack.addWidget(elBackText);
-		mdem->backLabels.append(elBackText);
-	}
-
-	mdem->vMdem.addWidget(&mdem->wFront);
-	mdem->vMdem.addWidget(&mdem->wBack);
-	mdem->vMdem.setContentsMargins(0, 0, 0, 0);
-	mdem->vMdem.setSpacing(0);
-
-	mdem->wBack.hide();
-	mdem->wMdem.hide();
-
-	// Connect button to toggle view
-	QObject::connect(&mdem->showButton, &QToolButton::clicked, [mdem]() {
-		if (mdem->wBack.isVisible()) {
-			mdem->wBack.hide();
-			mdem->showButton.setText("Show");
-		} else {
-			mdem->wBack.show();
-			mdem->showButton.setText("Hide");
-		}
-		showBacklabels(mdem);
-	});
-	return mdem;
-}
-
-
-void CreateMdems(std::vector<Question*>& questions) {
-	hMdemScroll->removeItem(mdemSpacer);
-
-    for (Mdem *mdem : mdems) {
-        if (mdem->wMdem.isVisible()) {
-            mdem->wMdem.hide();
-        }
-    }
-
-	if (questions.size() > mdems.size()) {
-		auto amount = questions.size() - mdems.size(); 
-		for (size_t i = 0; i < amount; ++i) {
-			auto mdem = makeMdem();
-			mdems.append(mdem);
-			hMdemScroll->addWidget(&mdem->wMdem);
-		}
-	}
-
-	for (size_t i = 0; i < questions.size(); ++i) {
-		mdems[i]->question = questions[i];
-		setupMdem(mdems[i], questions[i]);
-		if (!mdems[i]->wMdem.isVisible()) {
-		   mdems[i]->wMdem.show();
-    	}
-	}
-
-	hMdemScroll->addItem(mdemSpacer);
-}
-
-void update(bool isChanged) {
-	if (currentPage > -1) {
-		SwitchPage(currentPage);
-	}
-	if (currentMdem.length() > 0) {
-		updateMdemInfo(getFilename(currentMdem), isChanged);
-	}
-}
-
-void SwitchPage(int pageIdx) {
-    currentPage = pageIdx;
-
-    // Hide all pagination buttons
-    for (auto& button : paginationButtons) {
-        button->hide();
-    }
-
-    int l = 0;
-    char buffer[50];
-    snprintf(buffer, sizeof(buffer), "Page: %d", pageIdx + 1);
-    paginationLabel->setText(buffer);
-
-    // Hide widgets in mdems
-    for (auto& mdem : mdems) {
-        if (mdem->wBack.isVisible()) {
-            mdem->wBack.hide();
-            mdem->showButton.setText("Show");
-        }
-    }
-
-    // Update pagination buttons
-    for (int k = -DISTANCE; k <= DISTANCE; ++k) {
-        if (pageIdx + k >= 0 && pageIdx + k < pages.size()) {
-            auto button = paginationButtons[l];
-            snprintf(buffer, sizeof(buffer), "%d", pageIdx + k + 1);
-            button->setText(buffer);
-
-            if (pageIdx + k != pageIdx) {
-                button->show();
-            } else {
-                button->hide();
-            }
-            ++l;
-        }
-    }
-
-    // Handle first and last buttons
-    if (pageIdx > 0 && pages.size() > 1) {
-        firstButton->show();
-    } else {
-        firstButton->hide();
-    }
-
-    if (pageIdx < pages.size() - 1 && pages.size() > 1) {
-        lastButton->show();
-    } else {
-        lastButton->hide();
-    }
-
-    // Handle next and previous buttons
-    if (!pages.empty() && currentPage < pages.size() - 1) {
-        nextButton->show();
-    } else {
-        nextButton->hide();
-    }
-
-    if (!pages.empty() && currentPage >= 1) {
-        prevButton->show();
-    } else {
-        prevButton->hide();
-    }
-
-    Page page;
-	if (pages.size() <= 0) {
-		page = Page();
-	} else if (pageIdx < pages.size()){
-		page = pages[pageIdx];
-	} else {
-		if (pageIdx - 1 < pages.size()) {
-			page = pages[pageIdx -1];
-		} else {
-			page = pages[0];
-		}
-	}
-
-    std::vector<Question*> pageSlice(
-		currentMdemBuffer->questions.begin() + page.start,
-		currentMdemBuffer->questions.begin() + page.end
-	);
-    CreateMdems(pageSlice);
-}
-
-void reloadMdem(std::string path) {
-	if (path == "") {
-		return;
-	}
-	
-	auto toRemove = std::vector<std::string>();
-	for (auto it = buffers.begin(); it != buffers.end(); ++it) {
-		auto pair = *it;
-		if (currentMdem.compare(path) != 0 &&
-			(!pair.second->isModified || pair.second->error)) {
-			toRemove.push_back(pair.first);
-		}
-	}
-	for (auto key: toRemove) {
-		buffers.erase(key);
-	}
-
-	MdemBuffer *buffer;
-	auto filename = getFilename(path);
-	if (currentMdem.compare(path) == 0) {
-		buffer = currentMdemBuffer;
-		currentMdem = path;
-		if (buffers.contains(path)) {
-			buffers.erase(path);
-		}
-	} else if (!buffers.contains(path)) {
-		buffer = new MdemBuffer;
-		buffers[path] = buffer;
-		currentMdemBuffer = buffer;
-		currentMdem = path;
-	} else {
-		buffer = buffers[path];
-		currentMdemBuffer = buffer;
-		makePages();
-		SwitchPage(0);
-		updateMdemInfo(getFilename(filename), buffer->isModified);
-		currentMdem = path;
-		errorView->box.hide();
-		return;
-	}
-
-	auto file = std::ifstream(path);
-	std::string content;
-
-	// Reset the mdem list.
-	for (auto mdem: mdems) {
-		mdem->wMdem.hide();
-	}
-	for (auto question: currentMdemBuffer->questions) {
-		delete question;
-	}
-	currentMdemBuffer->questions.clear();
-
-	if (file) {
-		std::stringstream buffer;
-		buffer << file.rdbuf();
-		content = buffer.str();
-		auto res = transpile(content, true);
-
-		currentMdemBuffer->error = res.error.length() > 0;
-		if (res.error == "") {
-			if (res.value.lastTrainedAt == 0) {
-				currentMdemBuffer->trainedAt = 0;
-			} else {
-				auto timezoneOffset = settings->value("timezone").toInt();
-				currentMdemBuffer->trainedAt = res.value.lastTrainedAt - 3600 * timezoneOffset;
-			}
-			std::cout << std::format("Last trained at: {}", currentMdemBuffer->trainedAt) << std::endl;
-
-			currentMdemBuffer->questions = res.value.questions;
-			errorView->box.hide();
-		} else {
-			currentMdemBuffer->trainedAt = 0;
-			std::cout << std::format("Compilation error: {}", res.error) << std::endl;
-
-			for (auto question: res.value.questions) {
-				delete question;
-			}
-
-			// Show errors.
-			hMdemScroll->removeItem(mdemSpacer);
-			errorView->label.setText(
-				QString::fromStdString(
-					std::format(
-						"Error while transpiling {}: {} ({}:{})",
-						filename,
-						res.error,
-						res.row,
-						res.column
-					)
-				)
-			);
-			errorView->box.show();
-
-			hMdemScroll->addWidget(&errorView->box);
-			hMdemScroll->addItem(mdemSpacer);
-		}
-		makePages();
-		SwitchPage(0);
-		updateMdemInfo(filename, false);
-	} else {
-		std::cout << std::format("Could not open the file: {}", currentPath) << std::endl;
-	}
-
-	hideQuestionElements();
-	trainWindow->close();
-}
-
-void pickDirectory(QString directory) {
-	currentPath = directory.toStdString();
-
-	// Update tree view.
-	if (directory.length() <= 0) {
-		membaseLabel->setText(directory);
-		return;
-	}
-    mdemList->setRootIndex(model->setRootPath(directory));
-	std::smatch matches;
-	
-	// Update label.
-	membaseLabel->setText(QString::fromStdString(
-		std::format(
-			"memorybase: {}",
-			getFilename(currentPath)
-		)
-	));
-
-	reloadMdem("");
-}
-
-void setupEditorSave() {
-	auto res = transpile(editor->text().toStdString(), true);
-	if (res.error.length() > 0) {
-		currentMdemBuffer->trainedAt = 0;
-		for (auto question: res.value.questions) {
-			delete question;
-		}
-		QMessageBox::information(
-			nullptr,
-			"Editing error",
-			QString::fromStdString(res.error)
-		);
-	} else {
-		if (editMdem) {
-			if (res.value.questions.size() <= 0) {
-				QMessageBox::information(
-					nullptr,
-					"Editing error",
-					"There are no questions in your input."
-				);
-			} else if (res.value.questions.size() == 1) {
-				auto oldQuestion = editMdem->question;
-				editMdem->question = res.value.questions[0];
-				for (int i = 0; i < currentMdemBuffer->questions.size(); ++i) {
-					if (currentMdemBuffer->questions[i] == oldQuestion) {
-						currentMdemBuffer->questions.erase(currentMdemBuffer->questions.begin() + i);
-						delete oldQuestion;
-						currentMdemBuffer->questions.insert(currentMdemBuffer->questions.begin() + i, res.value.questions[0]);
-						break;
-					}
-				}
-				setupMdem(editMdem, res.value.questions[0]);
-				showBacklabels(editMdem);
-				editorWindow->hide();
-				updateMdemInfo(getFilename(currentMdem), true);
-			} else {
-				QMessageBox::information(
-					nullptr,
-					"Editing error",
-					"There are more than question in your input. Please enter one."
-				);
-			}
-		} else {
-			if (res.value.questions.size() <= 0) {
-				QMessageBox::information(
-					nullptr,
-					"Editing error",
-					"There are no questions in your input."
-				);
-			} else {
-				currentMdemBuffer->questions.insert(
-					currentMdemBuffer->questions.begin(),
-					res.value.questions.begin(),
-					res.value.questions.end()
-				);
-				makePages();
-				SwitchPage(0);
-				editorWindow->hide();
-				updateMdemInfo(getFilename(currentMdem), true);
-			}
-		}
-	}
-};
-
-void saveMdem() {
-	auto filename = getFilename(currentMdem);
-	std::ofstream out(currentMdem);
-	out << outputMdem(currentMdemBuffer->questions, currentMdemBuffer->trainedAt);
-	updateMdemInfo(getFilename(currentMdem), false);
-}
+#include "mdemList.h"
 
 int main(int argc, char *argv[]) {
-
-    QApplication app(argc, argv);
-    QMainWindow window;
-
-	auto* settingsWindow = new QWidget;
-
-	{ // Menu bar.
-		QMenuBar *menuBar = new QMenuBar;
-		QFileDialog *fileDialog = new QFileDialog;
-
-		QMenu *menu = new QMenu("File");
-		QAction *actionOpen = menu->addAction("Open memorybase");
-		QObject::connect(actionOpen, &QAction::triggered, [fileDialog]() {
-			fileDialog->setDirectory(QDir::homePath());
-			fileDialog->setFileMode(QFileDialog::FileMode::Directory);
-			fileDialog->open();
-			QObject::disconnect(fileDialog, 0, 0, 0);		
-			fileDialog->connect(
-				fileDialog,
-				&QFileDialog::fileSelected,
-				pickDirectory
-			);
-		});
-
-		QAction *openSettings = menu->addAction("Settings");
-		QObject::connect(
-			openSettings,
-			&QAction::triggered,
-			[settingsWindow]() {
-			settingsWindow->show();
-		});
-
-		menuBar->addMenu(menu);
-		window.setMenuBar(menuBar);
-	}
-
-    { // Settings window.
-		QString configDir = QStandardPaths::writableLocation(QStandardPaths::AppConfigLocation);
-		QDir().mkpath(configDir);
-		QString settingsFile = configDir + "/mdem.ini";
-		settings = new QSettings(settingsFile, QSettings::IniFormat);
-        settingsWindow->setWindowTitle("Settings");
-
-        auto formLayout = new QFormLayout;
-
-        auto characterWrap = new QSpinBox;
-        characterWrap->setRange(30, 150); 
-        formLayout->addRow("Character wrap in code gen [30-150]:", characterWrap);
-
-        auto* timezone = new QSpinBox;
-        timezone->setRange(-12, 12); 
-        formLayout->addRow("Timezone as number (e.g. +2 as 2):", timezone);
-
-        auto* notRemembered = new QDoubleSpinBox;
-        notRemembered->setRange(0, 100); 
-        formLayout->addRow("Not remembered:", notRemembered);
-
-        auto* hard = new QDoubleSpinBox;
-        hard->setRange(0, 100); 
-        formLayout->addRow("Hard:", hard);
-
-        auto* medium = new QDoubleSpinBox;
-        medium->setRange(0, 100); 
-        formLayout->addRow("Medium:", medium);
-
-        auto* easy = new QDoubleSpinBox;
-        easy->setRange(0, 100); 
-        formLayout->addRow("Easy:", easy);
-
-        auto* btnSaveSettings = new QPushButton("Save");
-        auto* mainLayout = new QVBoxLayout;
-
-		// @Improve: validate setting values
-		characterWrap->setValue(settings->value(SETTING_CHARACTER_WRAP).toInt());
-		timezone->setValue(settings->value(SETTING_TIMEZONE).toInt());
-		notRemembered->setValue(settings->value(SETTING_NOT_REMEMBERED).toDouble());
-		hard->setValue(settings->value(SETTING_HARD).toDouble());
-		medium->setValue(settings->value(SETTING_MEDIUM).toDouble());
-		easy->setValue(settings->value(SETTING_EASY).toDouble());
-
-		auto saveSettings = [characterWrap, timezone, notRemembered, hard, medium, easy]() {
-			settings->setValue(SETTING_CHARACTER_WRAP, characterWrap->value());
-			settings->setValue(SETTING_TIMEZONE,       timezone->value());
-			settings->setValue(SETTING_NOT_REMEMBERED, notRemembered->value());
-			settings->setValue(SETTING_HARD,           hard->value());
-			settings->setValue(SETTING_MEDIUM,         medium->value());
-			settings->setValue(SETTING_EASY,           easy->value());
-		};
-
-		QObject::connect(
-			btnSaveSettings,
-			&QPushButton::clicked,
-			[saveSettings]() {
-				saveSettings();
-			}
-		);
-
-		QShortcut* shortcutSave = new QShortcut(QKeySequence("Ctrl+S"), settingsWindow);
-		QObject::connect(shortcutSave, &QShortcut::activated, [saveSettings]() {
-			saveSettings();
-		});
-
-        mainLayout->addLayout(formLayout);
-        mainLayout->addWidget(btnSaveSettings);
-
-        settingsWindow->setLayout(mainLayout);
-    }
-
-	{ // Setup editor.
-		editorWindow = new QMainWindow;
-
-		editorWindow->setWindowTitle("QScintilla Simple Editor");
-		editorWindow->resize(800, 600);
-		QWidget *wEditor = new QWidget;
-		QVBoxLayout *vlEditor = new QVBoxLayout;
-		wEditor->setLayout(vlEditor);
-		
-		QsciLexerCPP *lexer = new QsciLexerCPP;
-		editor = new QsciScintilla;
-		editor->setLexer(lexer);
-		editor->setUtf8(true);
-		editor->setMarginWidth(0, 15);
-		editor->zoomIn(2);
-
-		QHBoxLayout *buttonLayout = new QHBoxLayout;
-		QWidget *editorButtons = new QWidget;
-		auto btnSaveEditor = new QPushButton;
-
-		editorButtons->setLayout(buttonLayout);
-		btnSaveEditor->setText(QString::fromStdString("Save"));
-		QObject::connect(
-			btnSaveEditor,
-			&QToolButton::clicked,
-			setupEditorSave
-		);
-		buttonLayout->addWidget(btnSaveEditor);
-
-		vlEditor->addWidget(editor);
-		vlEditor->addWidget(editorButtons);
-
-		QShortcut* shortcutSave = new QShortcut(QKeySequence("Ctrl+S"), editorWindow);
-		QObject::connect(shortcutSave, &QShortcut::activated, []() {
-			if (editor->isVisible()) {
-				setupEditorSave();
-			}
-		});
-
-		editorWindow->setCentralWidget(wEditor);
-	}
-
-    QSplitter *hSplitter = new QSplitter();
-	QWidget     *leftWidget = new QWidget();
-	{ // Left side.
-		QVBoxLayout *leftLayout = new QVBoxLayout();
-		QWidget     *leftTop    = new QWidget();
-		QVBoxLayout *vLeftTop   = new QVBoxLayout();
-		mdemList                = new QTreeView();
-		membaseLabel               = new QLabel();
-		model                   = new QFileSystemModel();
-		membaseLabel->setStyleSheet(
-			"font-size: 17px;"
-			"font-weight: 400;"
-		);
-		mdemSpacer = new QSpacerItem(50, 50, QSizePolicy::Minimum, QSizePolicy::Expanding);
-		
-		leftWidget->setLayout(leftLayout);
-		leftLayout->addWidget(leftTop);
-		leftTop->setLayout(vLeftTop);
-		leftTop->setMinimumSize(0, 40);
-		vLeftTop->addWidget(membaseLabel);
-		// Hide all columns except the first one
-		mdemList->setModel(model);
-
-		QObject::connect(
-			mdemList,
-			&QTreeView::doubleClicked,
-			[](const QModelIndex &index) {
-				auto fileInfo = model->fileInfo(index);
-				reloadMdem(fileInfo.filePath().toStdString());
-			}
-		);
-
-		for (int col = 1; col < model->columnCount(); ++col) {
-			mdemList->hideColumn(col);
-		}
-		model->setHeaderData(0, Qt::Horizontal, QObject::tr("Custom Name"));
-		leftLayout->addWidget(mdemList);
-	}
-
-
-    // RightSide
-    QWidget     *rightWidget = new QWidget();
-    QVBoxLayout *rightLayout = new QVBoxLayout();
-    rightWidget->setLayout(rightLayout);
-
-	{ // Mdem list top.
-		QWidget *top      = new QWidget();
-		QHBoxLayout *hTop = new QHBoxLayout();
-		deckListLabel     = new QLabel();
-		deckListLabel->setStyleSheet(
-			"font-size: 17px;"
-			"font-weight: 400;"
-		);
-		top->setMinimumSize(0, 40);
-		top->setLayout(hTop);
-		rightLayout->addWidget(top);
-
-		hTop->addWidget(deckListLabel);
-		hTop->addStretch(1);
-
-		add = new QToolButton;
-		btnSaveFile = new QToolButton;
-		load  = new QToolButton;
-		auto cbAlgorithm = new QComboBox;
-		practice = new QToolButton;
-
-		// Buttons
-		auto buttons         = new QWidget();
-		auto vlButtons       = new QVBoxLayout();
-		buttons->setLayout(vlButtons);
-		auto buttonsTop      = new QWidget();
-		auto hlButtonsTop    = new QHBoxLayout();
-		buttonsTop->setLayout(hlButtonsTop);
-		auto buttonsBottom   = new QWidget();
-		auto hlButtonsBottom = new QHBoxLayout();
-		buttonsBottom->setLayout(hlButtonsBottom);
-		add->setText("Add");
-		btnSaveFile->setText("Save");
-		load->setText("Load");
-		hlButtonsTop->addWidget(add);
-		hlButtonsTop->addWidget(btnSaveFile);
-		hlButtonsTop->addWidget(load);
-		cbAlgorithm->addItem("Spaced",  SPACED);
-		cbAlgorithm->addItem("Random",  RANDOM);
-		cbAlgorithm->addItem("Primary", PRIMARY);
-		practice->setText("Practice");
-		hlButtonsBottom->addWidget(cbAlgorithm);
-		hlButtonsBottom->addWidget(practice);
-		vlButtons->addWidget(buttonsTop);
-		vlButtons->addWidget(buttonsBottom);
-		hlButtonsTop->setContentsMargins(0, 0, 0, 0);
-		hlButtonsBottom->setContentsMargins(0, 5, 0, 0);
-
-		hTop->addWidget(buttons);
-
-		QObject::connect(add, &QToolButton::clicked, []() {
-			editMdem = nullptr;
-			editorWindow->show();
-			editor->setText("");
-		});
-		QObject::connect(load, &QToolButton::clicked, []() {
-			reloadMdem(currentMdem);
-		});
-		QObject::connect(btnSaveFile, &QToolButton::clicked, []() {
-			saveMdem();
-		});
-		QObject::connect(
-			practice,
-			&QToolButton::clicked,
-			[cbAlgorithm](bool checked) {
-				trainWindow->show();
-				trainWindow->resize(600, 300);
-				initiatePractice(
-					currentMdemBuffer,
-					static_cast<PracticeAlgorithm>(cbAlgorithm->currentData().toInt())
-				);
-			}
-		);
-	}
-
-	{ // Error.
-		errorView = new ErrorView;
-		errorView->box.setObjectName("error-box");
-		errorView->box.setLayout(&errorView->layout);
-		errorView->box.setMinimumHeight(30);
-		errorView->box.setStyleSheet(
-			QString(
-				"QWidget#error-box {"
-					"border: 1px solid red;"
-					"background: %2;"
-				"}"
-			).arg(MDEM_BACKGROUND)
-		);
-		errorView->layout.addWidget(&errorView->label);
-		errorView->label.setWordWrap(true);
-	}
-
-	{ // Mdems
-		QScrollArea *mdemScroll    = new QScrollArea();
-		QWidget     *mdemContainer = new QWidget();
-		hMdemScroll = new QVBoxLayout();
-		mdemScroll->setWidget(mdemContainer);
-		mdemScroll->setWidgetResizable(true);
-		mdemContainer->setLayout(hMdemScroll);
-		rightLayout->addWidget(mdemScroll);
-		hMdemScroll->addItem(mdemSpacer);
-	}
-
-	{ // Pagination 
-		hSplitter->addWidget(leftWidget);
-		hSplitter->addWidget(rightWidget);
-		hSplitter->setStretchFactor(0, 1);
-		hSplitter->setStretchFactor(1, 3);
-
-		auto pagination = new QWidget();
-		auto hPagination = new QHBoxLayout();
-		pagination->setLayout(hPagination);
-
-		firstButton = new QToolButton();
-		firstButton->setText(QString::fromStdString("<<"));
-		hPagination->addWidget(firstButton);
-		firstButton->hide();
-		QObject::connect(firstButton, &QToolButton::clicked, [](bool checked) {
-			if (pages.size() > 0) {
-				SwitchPage(0);
-			}
-		});
-
-		prevButton = new QToolButton();
-		prevButton->setText(QString::fromStdString("<"));
-		hPagination->addWidget(prevButton);
-		prevButton->hide();
-		QObject::connect(prevButton, &QToolButton::clicked, [](bool checked) {
-			if (pages.size() > 0) {
-				SwitchPage(currentPage - 1);
-			}
-		});
-
-		for (int i = 0; i < PER_PAGE; i++) {
-			auto elButton = new QToolButton();
-			elButton->setText(QString("%1").arg(i+1));
-			hPagination->addWidget(elButton);
-			elButton->hide();
-			QObject::connect(elButton, &QToolButton::clicked, [elButton](bool checked) {
-				auto pageNum = std::stoi(elButton->text().toStdString().c_str());
-				auto pageIdx = pageNum - 1;
-				if (pageIdx < pages.size()) {
-					SwitchPage(pageIdx);
-				}
-			});
-			paginationButtons.push_back(elButton);
-		}
-		
-		nextButton = new QToolButton();
-		nextButton->setText(QString::fromStdString(">"));
-		hPagination->addWidget(nextButton);
-		nextButton->hide();
-		QObject::connect(nextButton, &QToolButton::clicked, [](bool checked) {
-			if (pages.size() > 0) {
-				SwitchPage(currentPage + 1);
-			}
-		});
-
-		lastButton = new QToolButton();
-		lastButton->setText(QString::fromStdString(">>"));
-		hPagination->addWidget(lastButton);
-		lastButton->hide();
-		QObject::connect(lastButton, &QToolButton::clicked, [](bool checked) {
-			if (pages.size() > 0) {
-				SwitchPage(pages.size() - 1);
-			}
-		});
-		hPagination->addStretch(1);
-		paginationLabel = new QLabel();
-		hPagination->addWidget(paginationLabel);
-		rightLayout->addWidget(pagination);
-	}
-
-	initTrainWindow();
-
-    window.setCentralWidget(hSplitter);
-    window.show();
-
-	if (currentPath.length() > 0) {
-		pickDirectory(QString::fromStdString(currentPath));
-	}
-
-	QShortcut* shortcutSaveFile = new QShortcut(QKeySequence("Ctrl+S"), &window);
-	QObject::connect(shortcutSaveFile, &QShortcut::activated, []() {
-		saveMdem();
-	});
-    return app.exec();
+	auto *app = new QApplication(argc, argv);
+	initMdemListWindow();
+	app->exec();
+	return 0;
 }
diff --git a/src/qtapp/mdemList.cpp b/src/qtapp/mdemList.cpp
new file mode 100644
index 0000000..d6b7d07
--- /dev/null
+++ b/src/qtapp/mdemList.cpp
@@ -0,0 +1,1059 @@
+#include <cstdio>
+#include <ctime>
+#include <format>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <qabstractbutton.h>
+#include <qapplication.h>
+#include <qboxlayout.h>
+#include <qcombobox.h>
+#include <qdialog.h>
+#include <qlabel.h>
+#include <qlayoutitem.h>
+#include <qmainwindow.h>
+#include <qnamespace.h>
+#include <qobjectdefs.h>
+#include <qsettings.h>
+#include <qsizepolicy.h>
+#include <qt/QtWidgets/qwidget.h>
+#include <qtoolbutton.h>
+#include <qwidget.h>
+#include <qwindow.h>
+#include <qwindowdefs.h>
+#include <regex>
+#include <sstream>
+#include <string>
+
+#include <Qsci/qsciscintilla.h>
+#include <Qsci/qscilexercpp.h>
+#include <QApplication>
+#include <QMainWindow>
+#include <QVBoxLayout>
+#include <QHBoxLayout>
+#include <QLabel>
+#include <QToolButton>
+#include <QFileSystemModel>
+#include <QTreeView>
+#include <QSplitter>
+#include <QVariant>
+#include <QMessageBox>
+#include <QScrollArea>
+#include <QSpacerItem>
+#include <QFile>
+#include <QTime>
+#include <QRegularExpression>
+#include <QStringList>
+#include <QListView>
+#include <QWindow>
+#include <QMenuBar>
+#include <QMenu>
+#include <QFileDialog>
+#include <qabstractitemmodel.h>
+#include <QFormLayout>
+#include <QSettings>
+#include <QLineEdit>
+#include <QComboBox>
+#include <QSpinBox>
+#include <QDoubleSpinBox>
+#include <QCheckBox>
+#include <QPushButton>
+#include <QStandardPaths>
+#include <QShortcut>
+#include <QWidget>
+
+#include "settings.h"
+#include "mdemList.h"
+#include "trainWindow.h"
+#include "api.h"
+#include "parser.h"
+#include "qscilexer.h"
+
+#define TEXT_LG =        20
+#define ERROR_POOL_CHUNK 50
+#define DISTANCE         2
+#define PER_PAGE         8
+#define MDEM_BACKGROUND  "#F7F7F7"
+
+// Memorybase info.
+// @Improve: set the default directory for convenience. It should be configured by user
+// or set to "".
+std::string              currentPath   = "/home/jorenchik/Code/mdemory/memorybase/";
+std::string              currentMdem   = "";
+QFileSystemModel        *model;
+QTreeView               *mdemList;
+QLabel                  *membaseLabel;
+
+std::map<std::string, MdemBuffer*>  buffers;
+MdemBuffer                         *currentMdemBuffer;
+
+// Mdem scroll list.
+std::vector<Mdem*>  mdems = std::vector<Mdem*>();
+QVBoxLayout  *hMdemScroll;
+QSpacerItem  *mdemSpacer;
+ErrorView*    errorView;
+
+// Editor
+Mdem* editMdem;
+
+// Pagination 
+int                 currentPage   = -1;
+std::vector<Page>   pages;
+QList<QToolButton*> paginationButtons;
+QToolButton*        prevButton;
+QToolButton*        firstButton;
+QToolButton*        lastButton;
+QToolButton*        nextButton; 
+QLabel*             paginationLabel;
+
+// Top layout.
+QLabel       *deckListLabel;
+QToolButton  *add;
+QToolButton  *btnSaveFile;
+QToolButton  *load;
+QToolButton  *practice;
+
+QsciScintilla *editor;
+QMainWindow* editorWindow;
+
+const std::regex lastPathElementExp = std::regex("(.+\\/)*(.+)"); 
+
+void showBacklabels(Mdem *mdem) {
+	for (size_t i = 0; i < mdem->backLabels.size(); ++i) {
+		if (i < mdem->labelCount) {
+			if (!mdem->backLabels[i]->isVisible()) {
+				mdem->backLabels[i]->show();
+			}
+		} else {
+			if (mdem->backLabels[i]->isVisible()) {
+				mdem->backLabels[i]->hide();
+			}
+		}
+	}
+}
+
+std::string outputMdem(std::vector<Question*> questions, time_t time = 0) {
+	std::stringstream ss;
+
+	int wrap_width = 80;
+	if (settings->contains(SETTING_CHARACTER_WRAP)) {
+		wrap_width = settings->value(SETTING_CHARACTER_WRAP).toInt();
+	}
+
+	if (time > 0) {
+		auto timezoneOffset = settings->value(SETTING_TIMEZONE).toInt();
+		/*time = time + 3600 * timezoneOffset;*/
+		std::tm* tm = std::localtime(&time);
+		char buffer[100];
+		std::strftime(buffer, sizeof(buffer), "%d.%m.%Y %H\\:%M", tm);
+		auto time = std::string(buffer);
+		ss << time << std::endl;
+	}
+
+	for (auto question: questions) {
+		ss << std::endl;
+		std::string cooldownPart;
+		if (question->Cooldown != 0) {
+			cooldownPart = std::format(" [{:.2f}]", question->Cooldown);
+		}
+		ss << wrapText(
+			std::format("-{}{} >\n",
+			cooldownPart,
+			" " + escapeText(question->QuestionText)),
+			wrap_width
+		);
+		if (MultiElementQuestion* mw = dynamic_cast<MultiElementQuestion*>(question)) {
+			for (auto choice: mw->Choices) {
+				char opener;
+				if (choice.IsCorrect) {
+					opener = '+';
+				} else {
+					opener = '-';
+				}
+				std::string orderModifier;
+				if (mw->type == MultiElementType::Order) {
+					orderModifier = "^";
+				}
+				ss << 
+					wrapText(
+						std::format(
+							"\t{}{} {}\n",
+							opener,
+							orderModifier,
+							escapeText(choice.Answer)
+						)
+					, wrap_width);
+			}
+		} else if (GroupQuestion* gq = dynamic_cast<GroupQuestion*>(question)) {
+			for (auto group: gq->Groups) {
+				ss << wrapText(
+					std::format(
+						"\t- {}:\n",
+						escapeText(group.name)
+					)
+				, wrap_width);
+				for (auto element: group.elements) {
+					ss << wrapText(
+					std::format(
+						"\t\t- {}\n",
+						escapeText(element)
+					)
+					, wrap_width);
+				}
+			}
+		}
+	}
+	return ss.str();
+}
+
+void makePages() {
+    pages.clear();
+	auto len = currentMdemBuffer->questions.size();
+	auto pageAmount = len / PER_PAGE;
+	if (len % PER_PAGE != 0) {
+		pageAmount += 1;
+	}
+	for (size_t i = 0; i < pageAmount; i++) {
+		size_t startingIndex = PER_PAGE * i ;
+		size_t amount = PER_PAGE;
+		if (i == currentMdemBuffer->questions.size() / PER_PAGE) {
+            amount = currentMdemBuffer->questions.size() % PER_PAGE;
+        }
+        pages.push_back(Page{startingIndex, startingIndex + amount});
+    }
+}
+
+void setupMdem(Mdem *mdem, Question *question) {
+	std::stringstream ss;
+	if (question->Cooldown > 0) {
+		ss << std::format("[{:.2f}] ", question->Cooldown);
+	}
+	ss << question->QuestionText;
+	mdem->wFrontText.setText(
+		QString::fromStdString(ss.str())	
+	);
+	if (MultiElementQuestion* mw = dynamic_cast<MultiElementQuestion*>(question)) {
+		auto choices = mw->Choices;
+		for (size_t k = 0; k < choices.size(); ++k) {
+			auto answer = choices[k].Answer;
+			switch (mw->type) {
+				case MultiElementType::Order:
+					answer = std::format("{}. {}", k + 1, answer); 
+					break;
+				case MultiElementType::MultiChoice:
+					if (choices[k].IsCorrect) {
+						answer = std::format("+ {}", answer); 
+					} else {
+						answer = std::format("- {}", answer); 
+					}
+					break;
+				case MultiElementType::Regular:
+					answer = std::format("- {}", answer); 
+					break;
+			} 
+			if (k < mdem->backLabels.size()) {
+				mdem->backLabels[k]->setText(QString::fromStdString(answer));
+			} else {
+				auto label = new QLabel();
+				label->setText(QString::fromStdString(answer));
+				mdem->backLabels.push_back(label);
+				mdem->wBack.layout()->addWidget(label);
+			}
+		}
+		mdem->labelCount = choices.size();
+	} else if (GroupQuestion* mw = dynamic_cast<GroupQuestion*>(question)) {
+		auto groups = mw->Groups;
+		std::vector<std::string> elements;
+		for (size_t k = 0; k < groups.size(); ++k) {
+			auto answer = groups[k].name;
+			elements.push_back(std::format("- {}:", answer)); 
+			for (size_t l = 0; l < groups[k].elements.size(); ++l) {
+				elements.push_back(std::format("    - {}", groups[k].elements[l])); 
+			}
+		}
+		for (size_t k = 0; k < elements.size(); ++k) {
+			if (k < mdem->backLabels.size()) {
+				mdem->backLabels[k]->setText(QString::fromStdString(elements[k]));
+			} else {
+				auto label = new QLabel();
+				label->setText(QString::fromStdString(elements[k]));
+				mdem->backLabels.push_back(label);
+				mdem->wBack.layout()->addWidget(label);
+			}
+		}
+		mdem->labelCount = elements.size();
+	}
+}
+
+void SwitchPage(int pageIdx);
+
+std::string getFilename(std::string path) {
+	std::smatch matches;
+	auto filenameMatched = std::regex_search(path, matches, lastPathElementExp); 
+	return matches[2].str();
+}
+
+void updateMdemInfo(std::string filename, bool isChanged) {
+	currentMdemBuffer->isModified = isChanged;
+	if (filename.length() > 0) {
+		std::stringstream ss;
+		ss << std::format("mdem: {}", filename); 
+		if (isChanged) {
+			ss << "*";
+		}
+		if (currentMdemBuffer->trainedAt > 0) {
+			std::tm* tm = std::localtime(&currentMdemBuffer->trainedAt);
+			char buffer[100];
+			std::strftime(buffer, sizeof(buffer), "%d.%m.%Y %H:%M", tm);
+			ss << std::endl << "Last practiced: " << std::string(buffer);
+		}
+		deckListLabel->setText(QString::fromStdString(ss.str()));
+	} else {
+		deckListLabel->setText("");
+	}
+}
+
+Mdem* makeMdem() {
+	auto mdem = new Mdem;
+	mdem->wMdem.setLayout(&mdem->vMdem);
+	
+	QString id = QString("mdem_%1").arg(1);
+	mdem->wMdem.setObjectName(id);
+
+	// Front
+	mdem->wFront.setMinimumHeight(60);
+	mdem->wFront.setLayout(&mdem->hFront);
+	mdem->wFront.setProperty("first", "true");
+	mdem->wMdem.setStyleSheet(QString(
+		"QWidget#%1 > QWidget {"
+			"border-right:  1px solid gray;"
+			"border-bottom: 1px solid gray;"
+			"border-left:   1px solid gray;"
+			"background: %2;"
+		"} "
+		"QWidget#%1 > QWidget[first=\"true\"] {"
+			"border-top: 1px solid gray;"
+		"}"
+	).arg(id, MDEM_BACKGROUND));
+
+	// Add Front Content
+	mdem->hFront.addWidget(&mdem->wFrontText);
+	mdem->hFront.addStretch(1);
+
+	mdem->editButton.setText("Edit");
+	QObject::connect(
+		&mdem->editButton,
+		&QToolButton::clicked,
+		[mdem]() {
+			editMdem = mdem;
+			if (mdem->question) {
+				editor->setText(
+					QString::fromStdString(
+						outputMdem(std::vector<Question*>{mdem->question})
+					)
+				);
+				editorWindow->show();
+				editor->setCursorPosition(1, 2);
+			}
+		}
+	);
+	mdem->hFront.addWidget(&mdem->editButton);
+
+	mdem->deleteButton.setText("Delete");
+	QObject::connect(
+		&mdem->deleteButton,
+		&QToolButton::clicked,
+		[mdem]() {
+			if (mdem->question) {
+				Question* deleted = nullptr;
+				for (size_t i = 0; i < currentMdemBuffer->questions.size(); ++i) {
+					if (currentMdemBuffer->questions[i] == mdem->question) {
+						currentMdemBuffer->questions.erase(currentMdemBuffer->questions.begin() + i);
+						delete mdem->question;
+						mdem->question = nullptr;
+						updateMdemInfo(getFilename(currentMdem), true);
+						break;
+					}
+				}
+				makePages();
+				SwitchPage(currentPage);
+			}
+			if (editMdem == mdem) {
+				editorWindow->hide();
+			}
+		}
+	);
+	mdem->hFront.addWidget(&mdem->deleteButton);
+	
+	mdem->showButton.setText("Show");
+	mdem->hFront.addWidget(&mdem->showButton);
+
+	// Back
+	QVBoxLayout *hBack = new QVBoxLayout();
+	mdem->wBack.setLayout(&mdem->hBack);
+	mdem->vMdem.addWidget(&mdem->wBack);
+
+	// Add Back Content
+	for (size_t i = 0; i < 20; ++i) {
+		// @Improve: back label pooling
+		QLabel *elBackText = new QLabel();
+		mdem->hBack.addWidget(elBackText);
+		mdem->backLabels.push_back(elBackText);
+	}
+
+	mdem->vMdem.addWidget(&mdem->wFront);
+	mdem->vMdem.addWidget(&mdem->wBack);
+	mdem->vMdem.setContentsMargins(0, 0, 0, 0);
+	mdem->vMdem.setSpacing(0);
+
+	mdem->wBack.hide();
+	mdem->wMdem.hide();
+
+	// Connect button to toggle view
+	QObject::connect(&mdem->showButton, &QToolButton::clicked, [mdem]() {
+		if (mdem->wBack.isVisible()) {
+			mdem->wBack.hide();
+			mdem->showButton.setText("Show");
+		} else {
+			mdem->wBack.show();
+			mdem->showButton.setText("Hide");
+		}
+		showBacklabels(mdem);
+	});
+	return mdem;
+}
+
+
+void CreateMdems(std::vector<Question*>& questions) {
+	hMdemScroll->removeItem(mdemSpacer);
+
+    for (Mdem *mdem : mdems) {
+        if (mdem->wMdem.isVisible()) {
+            mdem->wMdem.hide();
+        }
+    }
+
+	if (questions.size() > mdems.size()) {
+		auto amount = questions.size() - mdems.size(); 
+		for (size_t i = 0; i < amount; ++i) {
+			auto mdem = makeMdem();
+			mdems.push_back(mdem);
+			hMdemScroll->addWidget(&mdem->wMdem);
+		}
+	}
+
+	for (size_t i = 0; i < questions.size(); ++i) {
+		mdems[i]->question = questions[i];
+		setupMdem(mdems[i], questions[i]);
+		if (!mdems[i]->wMdem.isVisible()) {
+		   mdems[i]->wMdem.show();
+    	}
+	}
+
+	hMdemScroll->addItem(mdemSpacer);
+}
+
+void update(bool isChanged) {
+	if (currentPage > -1) {
+		SwitchPage(currentPage);
+	}
+	if (currentMdem.length() > 0) {
+		updateMdemInfo(getFilename(currentMdem), isChanged);
+	}
+}
+
+void SwitchPage(int pageIdx) {
+    currentPage = pageIdx;
+
+    // Hide all pagination buttons
+    for (auto& button : paginationButtons) {
+        button->hide();
+    }
+
+    int l = 0;
+    char buffer[50];
+    snprintf(buffer, sizeof(buffer), "Page: %d", pageIdx + 1);
+    paginationLabel->setText(buffer);
+
+    // Hide widgets in mdems
+    for (auto& mdem : mdems) {
+        if (mdem->wBack.isVisible()) {
+            mdem->wBack.hide();
+            mdem->showButton.setText("Show");
+        }
+    }
+
+    // Update pagination buttons
+    for (int k = -DISTANCE; k <= DISTANCE; ++k) {
+        if (pageIdx + k >= 0 && pageIdx + k < pages.size()) {
+            auto button = paginationButtons[l];
+            snprintf(buffer, sizeof(buffer), "%d", pageIdx + k + 1);
+            button->setText(buffer);
+
+            if (pageIdx + k != pageIdx) {
+                button->show();
+            } else {
+                button->hide();
+            }
+            ++l;
+        }
+    }
+
+    // Handle first and last buttons
+    if (pageIdx > 0 && pages.size() > 1) {
+        firstButton->show();
+    } else {
+        firstButton->hide();
+    }
+
+    if (pageIdx < pages.size() - 1 && pages.size() > 1) {
+        lastButton->show();
+    } else {
+        lastButton->hide();
+    }
+
+    // Handle next and previous buttons
+    if (!pages.empty() && currentPage < pages.size() - 1) {
+        nextButton->show();
+    } else {
+        nextButton->hide();
+    }
+
+    if (!pages.empty() && currentPage >= 1) {
+        prevButton->show();
+    } else {
+        prevButton->hide();
+    }
+
+    Page page;
+	if (pages.size() <= 0) {
+		page = Page();
+	} else if (pageIdx < pages.size()){
+		page = pages[pageIdx];
+	} else {
+		if (pageIdx - 1 < pages.size()) {
+			page = pages[pageIdx -1];
+		} else {
+			page = pages[0];
+		}
+	}
+
+    std::vector<Question*> pageSlice(
+		currentMdemBuffer->questions.begin() + page.start,
+		currentMdemBuffer->questions.begin() + page.end
+	);
+    CreateMdems(pageSlice);
+}
+
+void reloadMdem(std::string path) {
+	if (path == "") {
+		return;
+	}
+	
+	auto toRemove = std::vector<std::string>();
+	for (auto it = buffers.begin(); it != buffers.end(); ++it) {
+		auto pair = *it;
+		if (currentMdem.compare(path) != 0 &&
+			(!pair.second->isModified || pair.second->error)) {
+			toRemove.push_back(pair.first);
+		}
+	}
+	for (auto key: toRemove) {
+		buffers.erase(key);
+	}
+
+	MdemBuffer *buffer;
+	auto filename = getFilename(path);
+	if (currentMdem.compare(path) == 0) {
+		buffer = currentMdemBuffer;
+		currentMdem = path;
+		if (buffers.contains(path)) {
+			buffers.erase(path);
+		}
+	} else if (!buffers.contains(path)) {
+		buffer = new MdemBuffer;
+		buffers[path] = buffer;
+		currentMdemBuffer = buffer;
+		currentMdem = path;
+	} else {
+		buffer = buffers[path];
+		currentMdemBuffer = buffer;
+		makePages();
+		SwitchPage(0);
+		updateMdemInfo(getFilename(filename), buffer->isModified);
+		currentMdem = path;
+		errorView->box.hide();
+		return;
+	}
+
+	auto file = std::ifstream(path);
+	std::string content;
+
+	// Reset the mdem list.
+	for (auto mdem: mdems) {
+		mdem->wMdem.hide();
+	}
+	for (auto question: currentMdemBuffer->questions) {
+		delete question;
+	}
+	currentMdemBuffer->questions.clear();
+
+	if (file) {
+		std::stringstream buffer;
+		buffer << file.rdbuf();
+		content = buffer.str();
+		auto res = transpile(content, true);
+
+		currentMdemBuffer->error = res.error.length() > 0;
+		if (res.error == "") {
+			if (res.value.lastTrainedAt == 0) {
+				currentMdemBuffer->trainedAt = 0;
+			} else {
+				auto timezoneOffset = settings->value("timezone").toInt();
+				currentMdemBuffer->trainedAt = res.value.lastTrainedAt - 3600 * timezoneOffset;
+			}
+			std::cout << std::format("Last trained at: {}", currentMdemBuffer->trainedAt) << std::endl;
+
+			currentMdemBuffer->questions = res.value.questions;
+			errorView->box.hide();
+		} else {
+			currentMdemBuffer->trainedAt = 0;
+			std::cout << std::format("Compilation error: {}", res.error) << std::endl;
+
+			for (auto question: res.value.questions) {
+				delete question;
+			}
+
+			// Show errors.
+			hMdemScroll->removeItem(mdemSpacer);
+			errorView->label.setText(
+				QString::fromStdString(
+					std::format(
+						"Error while transpiling {}: {} ({}:{})",
+						filename,
+						res.error,
+						res.row,
+						res.column
+					)
+				)
+			);
+			errorView->box.show();
+
+			hMdemScroll->addWidget(&errorView->box);
+			hMdemScroll->addItem(mdemSpacer);
+		}
+		makePages();
+		SwitchPage(0);
+		updateMdemInfo(filename, false);
+	} else {
+		std::cout << std::format("Could not open the file: {}", currentPath) << std::endl;
+	}
+
+	hideQuestionElements();
+	trainWindow->close();
+}
+
+void pickDirectory(QString directory) {
+	currentPath = directory.toStdString();
+
+	// Update tree view.
+	if (directory.length() <= 0) {
+		membaseLabel->setText(directory);
+		return;
+	}
+    mdemList->setRootIndex(model->setRootPath(directory));
+	std::smatch matches;
+	
+	// Update label.
+	membaseLabel->setText(QString::fromStdString(
+		std::format(
+			"memorybase: {}",
+			getFilename(currentPath)
+		)
+	));
+
+	reloadMdem("");
+}
+
+void setupEditorSave() {
+	auto res = transpile(editor->text().toStdString(), true);
+	if (res.error.length() > 0) {
+		currentMdemBuffer->trainedAt = 0;
+		for (auto question: res.value.questions) {
+			delete question;
+		}
+		QMessageBox::information(
+			nullptr,
+			"Editing error",
+			QString::fromStdString(res.error)
+		);
+	} else {
+		if (editMdem) {
+			if (res.value.questions.size() <= 0) {
+				QMessageBox::information(
+					nullptr,
+					"Editing error",
+					"There are no questions in your input."
+				);
+			} else if (res.value.questions.size() == 1) {
+				auto oldQuestion = editMdem->question;
+				editMdem->question = res.value.questions[0];
+				for (size_t i = 0; i < currentMdemBuffer->questions.size(); ++i) {
+					if (currentMdemBuffer->questions[i] == oldQuestion) {
+						currentMdemBuffer->questions.erase(currentMdemBuffer->questions.begin() + i);
+						delete oldQuestion;
+						currentMdemBuffer->questions.insert(currentMdemBuffer->questions.begin() + i, res.value.questions[0]);
+						break;
+					}
+				}
+				setupMdem(editMdem, res.value.questions[0]);
+				showBacklabels(editMdem);
+				editorWindow->hide();
+				updateMdemInfo(getFilename(currentMdem), true);
+			} else {
+				QMessageBox::information(
+					nullptr,
+					"Editing error",
+					"There are more than question in your input. Please enter one."
+				);
+			}
+		} else {
+			if (res.value.questions.size() <= 0) {
+				QMessageBox::information(
+					nullptr,
+					"Editing error",
+					"There are no questions in your input."
+				);
+			} else {
+				currentMdemBuffer->questions.insert(
+					currentMdemBuffer->questions.begin(),
+					res.value.questions.begin(),
+					res.value.questions.end()
+				);
+				makePages();
+				SwitchPage(0);
+				editorWindow->hide();
+				updateMdemInfo(getFilename(currentMdem), true);
+			}
+		}
+	}
+};
+
+void saveMdem() {
+	auto filename = getFilename(currentMdem);
+	std::ofstream out(currentMdem);
+	out << outputMdem(currentMdemBuffer->questions, currentMdemBuffer->trainedAt);
+	updateMdemInfo(getFilename(currentMdem), false);
+}
+
+
+QMainWindow *initMdemListWindow() {
+    QMainWindow* window = new QMainWindow;
+	auto *settingsWindow = initSettings();
+
+	{ // Menu bar.
+		QMenuBar *menuBar = new QMenuBar;
+		QFileDialog *fileDialog = new QFileDialog;
+
+		QMenu *menu = new QMenu("File");
+		QAction *actionOpen = menu->addAction("Open memorybase");
+		QObject::connect(actionOpen, &QAction::triggered, [fileDialog]() {
+			fileDialog->setDirectory(QDir::homePath());
+			fileDialog->setFileMode(QFileDialog::FileMode::Directory);
+			fileDialog->open();
+			QObject::disconnect(fileDialog, 0, 0, 0);		
+			fileDialog->connect(
+				fileDialog,
+				&QFileDialog::fileSelected,
+				pickDirectory
+			);
+		});
+
+		QAction *openSettings = menu->addAction("Settings");
+		QObject::connect(
+			openSettings,
+			&QAction::triggered,
+			[settingsWindow]() {
+			settingsWindow->show();
+		});
+
+		menuBar->addMenu(menu);
+		window->setMenuBar(menuBar);
+	}
+
+	{ // Setup editor.
+		editorWindow = new QMainWindow;
+
+		editorWindow->setWindowTitle("QScintilla Simple Editor");
+		editorWindow->resize(800, 600);
+		QWidget *wEditor = new QWidget;
+		QVBoxLayout *vlEditor = new QVBoxLayout;
+		wEditor->setLayout(vlEditor);
+		
+		QsciLexerCPP *lexer = new QsciLexerCPP;
+		editor = new QsciScintilla;
+		editor->setLexer(lexer);
+		editor->setUtf8(true);
+		editor->setMarginWidth(0, 15);
+		editor->zoomIn(2);
+
+		QHBoxLayout *buttonLayout = new QHBoxLayout;
+		QWidget *editorButtons = new QWidget;
+		auto btnSaveEditor = new QPushButton;
+
+		editorButtons->setLayout(buttonLayout);
+		btnSaveEditor->setText(QString::fromStdString("Save"));
+		QObject::connect(
+			btnSaveEditor,
+			&QToolButton::clicked,
+			setupEditorSave
+		);
+		buttonLayout->addWidget(btnSaveEditor);
+
+		vlEditor->addWidget(editor);
+		vlEditor->addWidget(editorButtons);
+
+		QShortcut* shortcutSave = new QShortcut(QKeySequence("Ctrl+S"), editorWindow);
+		QObject::connect(shortcutSave, &QShortcut::activated, []() {
+			if (editor->isVisible()) {
+				setupEditorSave();
+			}
+		});
+
+		editorWindow->setCentralWidget(wEditor);
+	}
+
+    QSplitter *hSplitter = new QSplitter();
+	QWidget     *leftWidget = new QWidget();
+	{ // Left side.
+		QVBoxLayout *leftLayout = new QVBoxLayout();
+		QWidget     *leftTop    = new QWidget();
+		QVBoxLayout *vLeftTop   = new QVBoxLayout();
+		mdemList                = new QTreeView();
+		membaseLabel               = new QLabel();
+		model                   = new QFileSystemModel();
+		membaseLabel->setStyleSheet(
+			"font-size: 17px;"
+			"font-weight: 400;"
+		);
+		mdemSpacer = new QSpacerItem(50, 50, QSizePolicy::Minimum, QSizePolicy::Expanding);
+		
+		leftWidget->setLayout(leftLayout);
+		leftLayout->addWidget(leftTop);
+		leftTop->setLayout(vLeftTop);
+		leftTop->setMinimumSize(0, 40);
+		vLeftTop->addWidget(membaseLabel);
+		// Hide all columns except the first one
+		mdemList->setModel(model);
+
+		QObject::connect(
+			mdemList,
+			&QTreeView::doubleClicked,
+			[](const QModelIndex &index) {
+				auto fileInfo = model->fileInfo(index);
+				reloadMdem(fileInfo.filePath().toStdString());
+			}
+		);
+
+		for (int col = 1; col < model->columnCount(); ++col) {
+			mdemList->hideColumn(col);
+		}
+		model->setHeaderData(0, Qt::Horizontal, QObject::tr("Custom Name"));
+		leftLayout->addWidget(mdemList);
+	}
+
+
+    // RightSide
+    QWidget     *rightWidget = new QWidget();
+    QVBoxLayout *rightLayout = new QVBoxLayout();
+    rightWidget->setLayout(rightLayout);
+
+	{ // Mdem list top.
+		QWidget *top      = new QWidget();
+		QHBoxLayout *hTop = new QHBoxLayout();
+		deckListLabel     = new QLabel();
+		deckListLabel->setStyleSheet(
+			"font-size: 17px;"
+			"font-weight: 400;"
+		);
+		top->setMinimumSize(0, 40);
+		top->setLayout(hTop);
+		rightLayout->addWidget(top);
+
+		hTop->addWidget(deckListLabel);
+		hTop->addStretch(1);
+
+		add = new QToolButton;
+		btnSaveFile = new QToolButton;
+		load  = new QToolButton;
+		auto cbAlgorithm = new QComboBox;
+		practice = new QToolButton;
+
+		// Buttons
+		auto buttons         = new QWidget();
+		auto vlButtons       = new QVBoxLayout();
+		buttons->setLayout(vlButtons);
+		auto buttonsTop      = new QWidget();
+		auto hlButtonsTop    = new QHBoxLayout();
+		buttonsTop->setLayout(hlButtonsTop);
+		auto buttonsBottom   = new QWidget();
+		auto hlButtonsBottom = new QHBoxLayout();
+		buttonsBottom->setLayout(hlButtonsBottom);
+		add->setText("Add");
+		btnSaveFile->setText("Save");
+		load->setText("Load");
+		hlButtonsTop->addWidget(add);
+		hlButtonsTop->addWidget(btnSaveFile);
+		hlButtonsTop->addWidget(load);
+		cbAlgorithm->addItem("Spaced",  SPACED);
+		cbAlgorithm->addItem("Random",  RANDOM);
+		cbAlgorithm->addItem("Primary", PRIMARY);
+		practice->setText("Practice");
+		hlButtonsBottom->addWidget(cbAlgorithm);
+		hlButtonsBottom->addWidget(practice);
+		vlButtons->addWidget(buttonsTop);
+		vlButtons->addWidget(buttonsBottom);
+		hlButtonsTop->setContentsMargins(0, 0, 0, 0);
+		hlButtonsBottom->setContentsMargins(0, 5, 0, 0);
+
+		hTop->addWidget(buttons);
+
+		QObject::connect(add, &QToolButton::clicked, []() {
+			editMdem = nullptr;
+			editorWindow->show();
+			editor->setText("");
+		});
+		QObject::connect(load, &QToolButton::clicked, []() {
+			reloadMdem(currentMdem);
+		});
+		QObject::connect(btnSaveFile, &QToolButton::clicked, []() {
+			saveMdem();
+		});
+		QObject::connect(
+			practice,
+			&QToolButton::clicked,
+			[cbAlgorithm]() {
+				trainWindow->show();
+				trainWindow->resize(600, 300);
+				initiatePractice(
+					currentMdemBuffer,
+					static_cast<PracticeAlgorithm>(cbAlgorithm->currentData().toInt())
+				);
+			}
+		);
+	}
+
+	{ // Error.
+		errorView = new ErrorView;
+		errorView->box.setObjectName("error-box");
+		errorView->box.setLayout(&errorView->layout);
+		errorView->box.setMinimumHeight(30);
+		errorView->box.setStyleSheet(
+			QString(
+				"QWidget#error-box {"
+					"border: 1px solid red;"
+					"background: %2;"
+				"}"
+			).arg(MDEM_BACKGROUND)
+		);
+		errorView->layout.addWidget(&errorView->label);
+		errorView->label.setWordWrap(true);
+	}
+
+	{ // Mdems
+		QScrollArea *mdemScroll    = new QScrollArea();
+		QWidget     *mdemContainer = new QWidget();
+		hMdemScroll = new QVBoxLayout();
+		mdemScroll->setWidget(mdemContainer);
+		mdemScroll->setWidgetResizable(true);
+		mdemContainer->setLayout(hMdemScroll);
+		rightLayout->addWidget(mdemScroll);
+		hMdemScroll->addItem(mdemSpacer);
+	}
+
+	{ // Pagination 
+		hSplitter->addWidget(leftWidget);
+		hSplitter->addWidget(rightWidget);
+		hSplitter->setStretchFactor(0, 1);
+		hSplitter->setStretchFactor(1, 3);
+
+		auto pagination = new QWidget();
+		auto hPagination = new QHBoxLayout();
+		pagination->setLayout(hPagination);
+
+		firstButton = new QToolButton();
+		firstButton->setText(QString::fromStdString("<<"));
+		hPagination->addWidget(firstButton);
+		firstButton->hide();
+		QObject::connect(firstButton, &QToolButton::clicked, []() {
+			if (pages.size() > 0) {
+				SwitchPage(0);
+			}
+		});
+
+		prevButton = new QToolButton();
+		prevButton->setText(QString::fromStdString("<"));
+		hPagination->addWidget(prevButton);
+		prevButton->hide();
+		QObject::connect(prevButton, &QToolButton::clicked, []() {
+			if (pages.size() > 0) {
+				SwitchPage(currentPage - 1);
+			}
+		});
+
+		for (size_t i = 0; i < PER_PAGE; i++) {
+			auto elButton = new QToolButton();
+			elButton->setText(QString("%1").arg(i+1));
+			hPagination->addWidget(elButton);
+			elButton->hide();
+			QObject::connect(elButton, &QToolButton::clicked, [elButton]() {
+				auto pageNum = std::stoi(elButton->text().toStdString().c_str());
+				auto pageIdx = pageNum - 1;
+				if (pageIdx < pages.size()) {
+					SwitchPage(pageIdx);
+				}
+			});
+			paginationButtons.push_back(elButton);
+		}
+		
+		nextButton = new QToolButton();
+		nextButton->setText(QString::fromStdString(">"));
+		hPagination->addWidget(nextButton);
+		nextButton->hide();
+		QObject::connect(nextButton, &QToolButton::clicked, []() {
+			if (pages.size() > 0) {
+				SwitchPage(currentPage + 1);
+			}
+		});
+
+		lastButton = new QToolButton();
+		lastButton->setText(QString::fromStdString(">>"));
+		hPagination->addWidget(lastButton);
+		lastButton->hide();
+		QObject::connect(lastButton, &QToolButton::clicked, []() {
+			if (pages.size() > 0) {
+				SwitchPage(pages.size() - 1);
+			}
+		});
+		hPagination->addStretch(1);
+		paginationLabel = new QLabel();
+		hPagination->addWidget(paginationLabel);
+		rightLayout->addWidget(pagination);
+	}
+
+	initTrainWindow();
+
+    window->setCentralWidget(hSplitter);
+    window->show();
+
+	if (currentPath.length() > 0) {
+		pickDirectory(QString::fromStdString(currentPath));
+	}
+
+	QShortcut* shortcutSaveFile = new QShortcut(QKeySequence("Ctrl+S"), window);
+	QObject::connect(shortcutSaveFile, &QShortcut::activated, []() {
+		saveMdem();
+	});
+
+	return window;
+}
diff --git a/src/qtapp/settings.cpp b/src/qtapp/settings.cpp
new file mode 100644
index 0000000..2b1e8e1
--- /dev/null
+++ b/src/qtapp/settings.cpp
@@ -0,0 +1,136 @@
+#include <qabstractbutton.h>
+#include <qapplication.h>
+#include <qboxlayout.h>
+#include <qcombobox.h>
+#include <qdialog.h>
+#include <qlabel.h>
+#include <qlayoutitem.h>
+#include <qmainwindow.h>
+#include <qnamespace.h>
+#include <qobjectdefs.h>
+#include <qsettings.h>
+#include <qsizepolicy.h>
+#include <qt/QtWidgets/qwidget.h>
+#include <qtoolbutton.h>
+#include <qwidget.h>
+#include <qwindow.h>
+#include <qwindowdefs.h>
+
+#include <Qsci/qsciscintilla.h>
+#include <Qsci/qscilexercpp.h>
+#include <QApplication>
+#include <QMainWindow>
+#include <QVBoxLayout>
+#include <QHBoxLayout>
+#include <QLabel>
+#include <QToolButton>
+#include <QFileSystemModel>
+#include <QTreeView>
+#include <QSplitter>
+#include <QVariant>
+#include <QMessageBox>
+#include <QScrollArea>
+#include <QSpacerItem>
+#include <QFile>
+#include <QTime>
+#include <QRegularExpression>
+#include <QStringList>
+#include <QListView>
+#include <QWindow>
+#include <QMenuBar>
+#include <QMenu>
+#include <QFileDialog>
+#include <qabstractitemmodel.h>
+#include <QFormLayout>
+#include <QSettings>
+#include <QLineEdit>
+#include <QComboBox>
+#include <QSpinBox>
+#include <QDoubleSpinBox>
+#include <QCheckBox>
+#include <QPushButton>
+#include <QStandardPaths>
+#include <QShortcut>
+#include <QWidget>
+
+#include "mdemList.h"
+#include "api.h"
+#include "qscilexer.h"
+
+QSettings *settings;
+
+QWidget *initSettings () { 
+	QString configDir = QStandardPaths::writableLocation(QStandardPaths::AppConfigLocation);
+	QDir().mkpath(configDir);
+	QString settingsFile = configDir + "/mdem.ini";
+	settings = new QSettings(settingsFile, QSettings::IniFormat);
+	auto* settingsWindow = new QWidget;
+	settingsWindow->setWindowTitle("Settings");
+
+	auto formLayout = new QFormLayout;
+
+	auto characterWrap = new QSpinBox;
+	characterWrap->setRange(30, 150); 
+	formLayout->addRow("Character wrap in code gen [30-150]:", characterWrap);
+
+	auto* timezone = new QSpinBox;
+	timezone->setRange(-12, 12); 
+	formLayout->addRow("Timezone as number (e.g. +2 as 2):", timezone);
+
+	auto* notRemembered = new QDoubleSpinBox;
+	notRemembered->setRange(0, 100); 
+	formLayout->addRow("Not remembered:", notRemembered);
+
+	auto* hard = new QDoubleSpinBox;
+	hard->setRange(0, 100); 
+	formLayout->addRow("Hard:", hard);
+
+	auto* medium = new QDoubleSpinBox;
+	medium->setRange(0, 100); 
+	formLayout->addRow("Medium:", medium);
+
+	auto* easy = new QDoubleSpinBox;
+	easy->setRange(0, 100); 
+	formLayout->addRow("Easy:", easy);
+
+	auto* btnSaveSettings = new QPushButton("Save");
+	auto* mainLayout = new QVBoxLayout;
+
+	// @Improve: validate setting values
+	characterWrap->setValue(settings->value(SETTING_CHARACTER_WRAP).toInt());
+	timezone->setValue(settings->value(SETTING_TIMEZONE).toInt());
+	notRemembered->setValue(settings->value(SETTING_NOT_REMEMBERED).toDouble());
+	hard->setValue(settings->value(SETTING_HARD).toDouble());
+	medium->setValue(settings->value(SETTING_MEDIUM).toDouble());
+	easy->setValue(settings->value(SETTING_EASY).toDouble());
+
+	auto saveSettings = [characterWrap, timezone, notRemembered, hard, medium, easy]() {
+		settings->setValue(SETTING_CHARACTER_WRAP, characterWrap->value());
+		settings->setValue(SETTING_TIMEZONE,       timezone->value());
+		settings->setValue(SETTING_NOT_REMEMBERED, notRemembered->value());
+		settings->setValue(SETTING_HARD,           hard->value());
+		settings->setValue(SETTING_MEDIUM,         medium->value());
+		settings->setValue(SETTING_EASY,           easy->value());
+	};
+
+	QObject::connect(
+		btnSaveSettings,
+		&QPushButton::clicked,
+		[saveSettings]() {
+			saveSettings();
+		}
+	);
+
+	QShortcut* shortcutSave = new QShortcut(QKeySequence("Ctrl+S"), settingsWindow);
+	QObject::connect(shortcutSave, &QShortcut::activated, [saveSettings]() {
+		saveSettings();
+	});
+
+	mainLayout->addLayout(formLayout);
+	mainLayout->addWidget(btnSaveSettings);
+
+	settingsWindow->setLayout(mainLayout);
+	return settingsWindow;
+}
+
+
diff --git a/src/qtapp/trainWindow.cpp b/src/qtapp/trainWindow.cpp
index 40b5a75..ecfd4dc 100644
--- a/src/qtapp/trainWindow.cpp
+++ b/src/qtapp/trainWindow.cpp
@@ -31,7 +31,8 @@
 #include <QPainter>
 #include <QShortcut>
 
-#include "main.h"
+#include "settings.h"
+#include "mdemList.h"
 #include "trainWindow.h"
 #include "parser.h"
 
@@ -75,15 +76,15 @@ public:
 		Qt::GlobalColor color;
 		auto colorIdx = index.data(Qt::UserRole + 1).toInt() ;
 		switch (colorIdx) {
-			case NEUTRAL:
+			case NEUTRAL: {
 				color = Qt::lightGray;
-				break;
-			case INCORRECT:
+			} break;
+			case INCORRECT: {
 				color = Qt::red;
-				break;
-			case CORRECT:
+			} break;
+			case CORRECT: {
 				color = Qt::green;
-				break;
+			} break;
 		}
 		painter->setOpacity(0.5);
 		if (color) {
@@ -248,7 +249,7 @@ QToolButton *btnEasy;
 
 QStandardItem* acquireItem() {
 	if (itemPool.size() <= 0) {
-		for (int i = 0; i < ITEM_POOL_CHUNK; ++i) {
+		for (size_t i = 0; i < ITEM_POOL_CHUNK; ++i) {
 			itemPool.push_back(new QStandardItem);
 		}
 	}
@@ -268,7 +269,7 @@ void releaseAllItems() {
 		std::endl;
 	auto releaseAllInModel = [](QStandardItemModel *model) {
 		auto itemCount = model->rowCount();
-		for (int i = 0; i < itemCount; ++i) {
+		for (size_t i = 0; i < itemCount; ++i) {
 			auto item = model->item(0);
 			model->takeRow(item->row());
 			releaseItem(&item);
@@ -357,7 +358,7 @@ void setupOrderQuestion(MultiElementQuestion *question) {
 		btnTriggerAnswer,
 		&QToolButton::clicked,
 		[question](bool checked) {
-			for (int i = 0; i < orderModel->rowCount(); ++i) {
+			for (size_t i = 0; i < orderModel->rowCount(); ++i) {
 				auto item = orderModel->item(i, 0);
 				auto text = item->text();
 				auto isCorrect = question->Choices[i].Answer.compare(text.toStdString()) == 0;
@@ -399,7 +400,7 @@ void setupMultiChoiceQuestion(MultiElementQuestion *question) {
 		btnTriggerAnswer,
 		&QToolButton::clicked,
 		[question](bool checked) {
-			for (int i = 0; i < multiChoiceModel->rowCount(); ++i) {
+			for (size_t i = 0; i < multiChoiceModel->rowCount(); ++i) {
 				auto item = multiChoiceModel->item(i, 0);
 				auto isCorrect = question->Choices[i].IsCorrect == (item->checkState() == Qt::Checked);
 				if (isCorrect) {
@@ -459,7 +460,7 @@ void setupGroupQuestion(GroupQuestion *question) {
 	for (int k = 0; k < groupViews.size(); k++) {
 		groupViews[k]->widget.hide();	
 	}
-	for (int i = 0; i < question->Groups.size(); i++) {
+	for (size_t i = 0; i < question->Groups.size(); i++) {
 		GroupView *groupView;
 		if (i < groupViews.size()) {
 			groupView = groupViews[i];
@@ -479,11 +480,11 @@ void setupGroupQuestion(GroupQuestion *question) {
 		btnTriggerAnswer,
 		&QToolButton::clicked,
 		[question](bool checked) {
-			for (int i = 0; i < groupItemModel->rowCount(); ++i) {
+			for (size_t i = 0; i < groupItemModel->rowCount(); ++i) {
 				auto item = groupItemModel->item(i, 0);
 				item->setData(INCORRECT, Qt::UserRole + 1);
 			}
-			for (int i = 0; i < groupViews.size(); i++) {
+			for (size_t i = 0; i < groupViews.size(); i++) {
 				auto groupView = groupViews[i];
 				auto group = question->Groups[i];
 				for (int j = 0; j < groupView->itemModel.rowCount(); ++j) {
@@ -568,7 +569,7 @@ void setupNextQuestion() {
 					setupQuestion(practiceBuffer->questions[currentQuestionIndex]);
 				}
 				updatePaginationVisibility();
-			} break;
+		} break;
 		case RANDOM: {
 				auto questionCandidates = practiceBuffer->questions;
 				if (currentQuestionIndex > -1) {
@@ -584,13 +585,13 @@ void setupNextQuestion() {
 						}
 					}
 				}
-			} break;
+		} break;
 		case SPACED: {
 				auto questionCandidates = std::vector<Question*>();
 				time_t time = getTime();
 				auto lastTrainedAt = practiceBuffer->trainedAt;
 				practiceBuffer->trainedAt = time;
-				for (int i = 0; i < practiceBuffer->questions.size(); ++i) {
+				for (size_t i = 0; i < practiceBuffer->questions.size(); ++i) {
 					auto cooldownSeconds = practiceBuffer->questions[i]->Cooldown * 3600;
 					auto cooldownEndsAt = lastTrainedAt + cooldownSeconds;
 					if (i != currentQuestionIndex && cooldownEndsAt <= time) {
@@ -615,7 +616,7 @@ void setupNextQuestion() {
 					}
 				}
 				update(true);
-			} break;
+		} break;
 	}
 }
 
diff --git a/src/transpiler/lexer.cpp b/src/transpiler/lexer.cpp
index 05d85fe..2df6326 100644
--- a/src/transpiler/lexer.cpp
+++ b/src/transpiler/lexer.cpp
@@ -113,6 +113,7 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
             column = 0;
         }
 
+		// Add escape char
 		if (c == '\\') {
 			i += 1;
 			if (i < fileRunes.size()) {
@@ -139,7 +140,7 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
 
         // EmitTokens
         switch (c) {
-            case '[':
+            case '[': {
                 makeTokenWithTokenBuffer(
                     TokenType::CooldownStart,
                     1,
@@ -149,8 +150,8 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
                 previousColumn = column;
                 textStarted = false;
                 identifierStarted = true;
-                break;
-            case ']':
+            } break;
+            case ']': {
                 if (!identifierStarted) {
 					return {
 						tokens,
@@ -168,8 +169,8 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
                 previousColumn = column;
                 textStarted = false;
                 identifierStarted = false;
-                break;
-            case '-':
+            } break;
+            case '-': {
                 makeTokenWithTokenBuffer(
                     TokenType::ElementDashStart,
                     1,
@@ -178,8 +179,8 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
                 previousRow = row;
                 previousColumn = column;
                 textStarted = false;
-                break;
-            case '^':
+            } break;
+            case '^': {
                 makeTokenWithTokenBuffer(
                     TokenType::ElementOrderModifier,
                     1,
@@ -188,8 +189,8 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
                 previousRow = row;
                 previousColumn = column;
                 textStarted = false;
-                break;
-            case ':':
+            } break;
+            case ':': {
                 makeTokenWithTokenBuffer(
                     TokenType::MatchGroupEnd,
                     1,
@@ -198,8 +199,8 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
                 previousRow = row;
                 previousColumn = column;
                 textStarted = false;
-                break;
-            case '>':
+            } break;
+            case '>': {
                 makeTokenWithTokenBuffer(
                     TokenType::QuestionEnd,
                     1,
@@ -207,8 +208,9 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
                 );
                 previousRow = row;
                 previousColumn = column;
-                break;
-            case '+':
+                textStarted = false;
+            } break;
+            case '+': {
                 makeTokenWithTokenBuffer(
                     TokenType::ElementPlusStart,
                     1,
@@ -217,7 +219,7 @@ Result<std::vector<Token>> tokenizeMdem(const std::string& fileRunes) {
                 previousRow = row;
                 previousColumn = column;
                 textStarted = false;
-                break;
+            } break;
         }
 
         column += 1;
@@ -262,7 +264,7 @@ std::string Token::ToString(const TokenType* ttype) {
         case TokenType::Cooldown:               return "cooldown";
         case TokenType::CooldownStart:          return "start of cooldown";
         case TokenType::CooldownEnd:            return "end of cooldown";
-        case TokenType::StartOfFile:                    return "start of the file";
+        case TokenType::StartOfFile:            return "start of the file";
         case TokenType::EndOfFile:              return "end of file";
         default:                                return "unrecognized token";
     }