Drawing out-of-bounds when changing Screen resolution

1)Set the Screen resolution to 800x600.
2)Run the attached app.Dont maximize it.
3)Dont close it
4)Change the Screen resolution to 1024 x 768
You will see that the contents of the window is painted OUT of bounds creating visible glitches.
If you move the borders of the app, you will see that really the content fits perfect the glitches.

Clipping issues?
App developed by Thomas Fabber.