diff --git a/src/cpp/qtapp/main.cpp b/src/cpp/qtapp/main.cpp
index ed8e449..1eb5a7a 100644
--- a/src/cpp/qtapp/main.cpp
+++ b/src/cpp/qtapp/main.cpp
@@ -2,14 +2,17 @@
 #include <format>
 #include <fstream>
 #include <iostream>
+#include <locale>
 #include <qabstractbutton.h>
 #include <qboxlayout.h>
 #include <qlabel.h>
 #include <qlayoutitem.h>
 #include <qmainwindow.h>
+#include <qnamespace.h>
 #include <qobjectdefs.h>
 #include <qsizepolicy.h>
 #include <qtoolbutton.h>
+#include <qwidget.h>
 #include <qwindow.h>
 #include <qwindowdefs.h>
 #include <regex>
@@ -35,7 +38,6 @@
 #include <QListView>
 #include <QWindow>
 #include <qabstractitemmodel.h>
-#include <system_error>
 
 #include "api.h"
 #include "parser.h"
@@ -87,12 +89,12 @@ public:
 		wFront->setProperty("first", "true");
         wMdem->setStyleSheet(QString(
             "QWidget#%1 > QWidget {"
-            "border-right:  1px solid gray;"
-            "border-bottom: 1px solid gray;"
-            "border-left:   1px solid gray;"
+				"border-right:  1px solid gray;"
+				"border-bottom: 1px solid gray;"
+				"border-left:   1px solid gray;"
             "} "
             "QWidget#%1 > QWidget[first=\"true\"] {"
-            "border-top: 1px solid gray;"
+				"border-top: 1px solid gray;"
             "}"
         ).arg(id));
 
@@ -140,7 +142,6 @@ public:
     }
 };
 
-
 QString                 workingPath   = "/home/jorenchik/Code/mdemory/memorybase";
 std::string             currentPath   = "";
 QList<Mdem*>            mdems         = QList<Mdem*>();
@@ -337,6 +338,52 @@ void SwitchPage(int pageIdx) {
 
 std::regex lastPathElementExp = std::regex("(.+\\/)*(.+)"); 
 
+struct ErrorView {
+	QWidget     box;
+	QVBoxLayout layout;
+	QLabel      label;
+};
+std::vector<ErrorView*> errorPool;
+std::vector<ErrorView*> errorViews;
+
+#define ERROR_POOL_CHUNK 50
+
+ErrorView *makeErrorView() {
+	auto errorView = new ErrorView;
+	errorView->box.setObjectName("error-box");
+	errorView->box.setLayout(&errorView->layout);
+	errorView->box.setMinimumHeight(30);
+	errorView->box.setStyleSheet(
+		"QWidget#error-box {"
+			"border: 1px solid red;"
+		"}"
+	);
+	errorView->layout.addWidget(&errorView->label);
+	return errorView; 
+};
+
+ErrorView* acquireError() {
+	if (errorPool.size() <= 0) {
+		for (int i = 0; i < ERROR_POOL_CHUNK; ++i) {
+			auto errorView = makeErrorView();
+			errorPool.push_back(errorView);
+			hMdemScroll->addWidget(&errorView->box);
+			errorView->box.hide();
+		}
+	}
+	auto item = errorPool.back();
+	errorPool.pop_back();
+	errorViews.push_back(item);
+	std::cout << std::format("Acquired, current pool size: {}\n", errorPool.size());
+	return item;
+}
+
+void releaseError(ErrorView** item) {
+	errorPool.push_back(*item);
+	(*item) = nullptr;
+	std::cout << std::format("Released, current pool size: {}\n", errorPool.size());
+}
+
 void loadMdem() {
 	auto file = std::ifstream(currentPath);
 	std::string content;
@@ -349,7 +396,23 @@ void loadMdem() {
 			delete question;
 		}
 		questions.clear();
+
+		std::smatch matches;
+		auto filenameMatched = std::regex_search(currentPath, matches, lastPathElementExp); 
+		auto filename = matches[2];
+		deckListLabel->setText(
+			QString::fromStdString(std::format("mdem: {}", filename.str()))
+		);
+
+		while (errorViews.size() > 0) {
+			auto errorView = errorViews.back();
+			errorViews.pop_back();
+			errorView->box.hide();
+			releaseError(&errorView);
+		}
+
 		if (res.error == "") {
+
 			time_t trainedAt;
 			if (res.value.lastTrainedAt == 0) {
 				trainedAt = 0;
@@ -360,13 +423,27 @@ void loadMdem() {
 			questions = res.value.questions;
 			makePages();
 			SwitchPage(0);
-			std::smatch matches;
-			auto filename = std::regex_search(currentPath, matches, lastPathElementExp); 
-			deckListLabel->setText(
-				QString::fromStdString(std::format("mdem: {}", matches[2].str()))
-			);
 		} else {
 			std::cout << std::format("Compilation error: {}", res.error) << std::endl;
+
+			// Show errors.
+			hMdemScroll->removeItem(mdemSpacer);
+			auto errorView = acquireError();
+			errorView->label.setText(
+				QString::fromStdString(
+					std::format(
+						"Error while transpiling {}: {} ({}:{})",
+						filename.str(),
+						res.error,
+						res.row,
+						res.column
+					)
+				)
+			);
+			errorView->box.show();
+			hMdemScroll->addWidget(&errorView->box);
+
+			hMdemScroll->addItem(mdemSpacer);
 			for (auto mdem: mdems) {
 				if (mdem->wMdem->isVisible()) {
 					mdem->wMdem->hide();
diff --git a/src/cpp/qtapp/trainWindow.cpp b/src/cpp/qtapp/trainWindow.cpp
index 77cbf89..34f6d15 100644
--- a/src/cpp/qtapp/trainWindow.cpp
+++ b/src/cpp/qtapp/trainWindow.cpp
@@ -244,7 +244,6 @@ std::vector<QStandardItem*> itemPool;
 
 #define ITEM_POOL_CHUNK 200
 
-
 QStandardItem* acquireItem() {
 	if (itemPool.size() <= 0) {
 		for (int i = 0; i < ITEM_POOL_CHUNK; ++i) {