private void AddSampleScopes(object sender, EventArgs e)
 {
     rtb.BackColor   = Color.AliceBlue;
     rtb.Text        = "Sample Input Text Active Scope\ntab HEY ";
     rtb.ActiveScope = rtb.RootScope.DefineInnerScope(18, 12);
     rtb.RootScope.DefineInnerScope(6, 5);
     rtb.InputMode = InputModes.RegexManipulation;
     rtb.Refresh();
 }
 public override void OnHighlightOff()
 {
     txt.Refresh();
 }