procedure TForm1.MakeTransparent1Click(Sender: TObject);
{ Make the area inside of the selection transparent. }
begin
  if ImageEnView1.Selected then
  begin
    Screen.Cursor := crHourGlass;
    try
      ImageEnView1.Proc.SaveUndoCaptioned('Make Selection Transparent ' +
        IntToStr(ImageEnView1.Proc.UndoCount));
      Undo1.Hint := 'Make Selection Transparent ' + IntToStr(ImageEnView1.Proc.UndoCount);
      ImageEnView1.EnableAlphaChannel := True;
      ImageEnView1.IO.Params.BitsPerSample := 8;
      ImageEnView1.IO.Params.SamplesPerPixel := 4;
      ImageEnVIew1.SetSelectedAreaAlpha(0);
      Undo1.Enabled := ImageEnView1.Proc.CanUndo;
      ImageEnView1.Bitmap.Modified := True;
    finally
      Screen.Cursor := crDefault;
    end;
  end
  else
  begin
    MessageDlg('There is no selection.  Please make a selection and try again.', mtWarning, [mbOK],
      0);
  end;
end