diff -r e34d6a30b96d -r 75efc3ba5a56 src/main.cpp
--- a/src/main.cpp	Mon Apr 10 14:46:36 2023 +0300
+++ b/src/main.cpp	Tue Apr 11 11:11:28 2023 +0300
@@ -238,7 +238,7 @@
 		QAction* action = new QAction{editingModeInfo.name, parent};
 		action->setCheckable(true);
 		action->setEnabled(false);
-		action->setData(static_cast<EditingMode>(i));
+		action->setData(QVariant::fromValue(static_cast<editing_mode_e>(i)));
 		action->setToolTip(editingModeInfo.tooltip);
 		action->setIcon(QPixmap{editingModeInfo.icon});
 		ui->editingModesToolBar->addAction(action);
@@ -371,7 +371,7 @@
 			&EditTools::suggestCursor,
 			data->canvas.get(),
 			&QWidget::setCursor);
-		data->tools->setEditMode(SelectMode);
+		data->tools->setEditMode(editing_mode_e::select);
 		const QFileInfo fileInfo{*state->documents.modelPath(modelId)};
 		auto* const subWindow = createSubWindow<ModelSubWindow>(state->mainWindow.mdiArea, modelId);
 		subWindow->setMinimumSize({96, 96});
@@ -468,13 +468,13 @@
 	}
 }
 
-static void checkEditingModeAction(MainState* state, const EditingMode mode)
+static void checkEditingModeAction(MainState* state, const editing_mode_e mode)
 {
 	const bool hasDocument = currentModelData(&state->mainWindow, &state->documents) != nullptr;
 	for (QAction* action : state->mainWindow.editingModesToolBar->actions())
 	{
 		action->setEnabled(hasDocument);
-		action->setChecked(hasDocument and action->data().value<EditingMode>() == mode);
+		action->setChecked(hasDocument and action->data().value<editing_mode_e>() == mode);
 	}
 }
 
@@ -502,6 +502,18 @@
 	update_model_grid_matrix(state);
 }
 
+static void replace_color_in_selected_code(QTextCursor* cursor, const ColorIndex color)
+{
+	const auto pattern = R"(^(\s*(?:1|2|3|4|5)\s+)\d+)";
+	static const QRegularExpression regular_expression{pattern, QRegularExpression::MultilineOption};
+	QString text = cursor->selectedText();
+	// Qt has decided to be "smart" and uses strange unicode characters instead of newlines
+	text.replace("\u2029", "\n");
+	text.replace(regular_expression, QStringLiteral(R"(\1%1)").arg(color.index));
+	cursor->removeSelectedText();
+	cursor->insertText(text);
+}
+
 int main(int argc, char *argv[])
 {
 	doQtRegistrations();
@@ -609,7 +621,7 @@
 		{
 			if (ModelData* data = currentModelData(&state.mainWindow, &state.documents))
 			{
-				const EditingMode mode = action->data().value<EditingMode>();
+				const editing_mode_e mode = action->data().value<editing_mode_e>();
 				data->tools->setEditMode(mode);
 				checkEditingModeAction(&state, mode);
 			}
@@ -631,7 +643,7 @@
 		}
 		else
 		{
-			checkEditingModeAction(&state, EditingMode::SelectMode);
+			checkEditingModeAction(&state, editing_mode_e::select);
 		}
 		state.mainWindow.modelEdit->setEnabled(modelSubWindow != nullptr);
 	});
@@ -713,6 +725,14 @@
 			set_grid_scale(&state, 0.1f);
 		}
 	);
+	QObject::connect(
+		state.mainWindow.action_make_stuff_red,
+		&QAction::triggered,
+		[&state]{
+			QTextCursor cursor = state.mainWindow.modelEdit->textCursor();
+			replace_color_in_selected_code(&cursor, ColorIndex{4});
+		}
+	);
 	restoreSettings(&state);
 	updateRenderPreferences(&state.mainWindow, &state.renderPreferences, &state.documents);
 	const int result = app.exec();