protected override void OnMouseUp (MouseEventArgs e)
{
if (this.close_on_mouse_release) {
this.DropDown.Dismiss (ToolStripDropDownCloseReason.ItemClicked);
this.Invalidate ();
this.close_on_mouse_release = false;
if (!this.IsOnDropDown && this.Parent is MenuStrip)
(this.Parent as MenuStrip).MenuDroppedDown = false;
}
if (!this.HasDropDownItems && Enabled)
base.OnMouseUp (e);
}