small improvement to the line numbering in the preview editor

src/gui/PreviewEdit.cc

@@ -170,15 +170,15 @@ void PreviewEdit::dragMoveEvent(QDragMoveEvent *event)
 int PreviewEdit::getSidePanelWidth()
 {
 	//since log10 returns 0 for numbers <10, add 1. For a nicer look, we add 0.5 char's width
-	const double digits = floor(log10(qMax(1, blockCount()))) + 1.5;
-	const int width = static_cast<int>(fontMetrics().boundingRect(QLatin1Char('0')).width() * digits);
+	const double digits = floor(log10(qMax(1, blockCount()))) + .5;
+	const int width = static_cast<int>(fontMetrics().boundingRect(QLatin1Char('M')).width() * digits);
 	return width;
 }
 
 void PreviewEdit::updateSidePanelWidth()
 {
 	//we add a small margin between the line number and the line itself
-	const int margin_width = fontMetrics().boundingRect(QLatin1Char('0')).width() / 2;
+	const int margin_width = fontMetrics().boundingRect(QLatin1Char('M')).width() / 2;
 	setViewportMargins(getSidePanelWidth()+margin_width, 0, 0, 0);
 }