public void DrawRectangleAtCaret()
{
if (MainTextBox != null && showLineThing.IsChecked == true)
{
Rect p = MainTextBox.GetCaretLocation();
Thickness t = new Thickness(0, p.Y - 1, 17, MainTextBox.ActualHeight - p.Bottom - 1);;
if (t.Top >= 0 && t.Bottom >= 0)
{
aditionalSelection.Visibility = Visibility.Visible;
aditionalSelection.Margin = t;
}
else
{
aditionalSelection.Visibility = Visibility.Collapsed;
}
}
else
{
aditionalSelection.Visibility = Visibility.Collapsed;
}
}