[MiNT] XaAES: form_alert() and window refresh

[Vincent Rivière <vincent.riviere@freesbee.fr>]

Hello.

I use ARAnyM and an EasyMiNT setup upgraded to FreeMiNT 1.17.

In TeraDesk, I open a files window in the middle of the screen. Then I do 
File > Quit/Shutdown. A modal dialog box is displayed. I can move it, but 
the window contents underneath are not refreshed, the window gets filled 
with grey.
When I click Cancel, everything goes back to normal.

--
Vincent Rivière