Event fired on click other area except one control

I use Jeremie CUSTOM_UI, and for the unknown reason, I should put below code in MouseDown event of PopupMenu otherwise it takes 2~3 seconds to display the lists(about 30 items).

App.UseGDIPlus = False

However, with the value of False of it, when I use other controls, App got stuck as I also use RubberView which needs TRUE value of the GDI+.
Currently, my workaround is to keep TRUE in Open or Action event of several Controls, but it doesn’t look neat.

Is there any event that only fires when I click other area or controls of my App except the PopupMenu control?
If there is, I think I can put UseGDIPlus=True in there to avoid App stuck.

Any idea?