private void MainRepl_PreviewKeyDown(object sender, KeyEventArgs args)
{
if (args.IsCtrl(Key.E)) {
RunSelection(MainRepl.Selection);
args.Handled = true;
} else if (args.Is(Key.Return)) {
InsertSmartLineBreak();
args.Handled = true;
} else if (args.Is(Key.Tab)) {
MainRepl.CaretPosition.InsertTextInRun(" ");
args.Handled = true;
} else if (args.IsCtrl(Key.S)) {
SaveDocument();
args.Handled = true;
} else if (args.IsCtrl(Key.Return)) {
RunCurrentLine();
args.Handled = true;
} else if (args.IsCtrl(Key.Space)) {
ChangeRunUnderCursorToDefaultTextStyle();
args.Handled = true;
}
}