minor optimization

src/gui/PreviewEdit.cc

@@ -178,7 +178,6 @@ int PreviewEdit::getSidePanelWidth()
 void PreviewEdit::updateSidePanelWidth()
 {
 	//we add a small margin between the line number and the line itself
-	const int margin_width = fontMetrics().boundingRect(QLatin1Char('M')).width() / 2;
 	setViewportMargins(getSidePanelWidth()+margin_width, 0, 0, 0);
 }
 

src/gui/PreviewEdit.h

@@ -61,6 +61,7 @@ class PreviewEdit : public QPlainTextEdit
 		QString file_path_; //file path without name
 		QString file_name_;
 		INISyntaxHighlighter *highlighter_ = nullptr;
+		const int margin_width = fontMetrics().boundingRect(QLatin1Char('M')).width();
 };