WindowServer: crash when changing the bounds

I have a strange problem. On a Studio X app I change the bounds of a window. This app and especially this function works very well on the most systems.
But I have on beta tester and if he activate the function for changing the bounds of a window then the app crashes or the window will be closed.
I don ´t find the reason for this. He sent me a crash log but this is not really easy to read and understand.
I built a debug app which has only one window with one button. By clicking this button the bounds of the window will be changed.

This is my code:

property clickStatus : true
on clicked theObject
	if clickStatus is true then
		set clickStatus to false
		set clickStatus to true
	end if
	set {tx, ty, txx, tyy} to bounds of window "mainWindow"
	tell window "mainWindow"
		if clickStatus is true then
			set bounds to {tx, (ty + 20), txx, tyy}
			set bounds to {tx, (ty - 20), txx, tyy}
		end if
	end tell
end clicked

If you need the crash log I could post it.
It would be very nice if someone can help me. Thanks.


P.S. This user has Shapeshifter installed.

What about QuarkXPress?

Why QuarkXPress? Is this a problem if QuarkXPress is installed?
I will ask the user if he has QuarkXPress.

Maybe (or not). QuarkXPress is known to cause issues with the keyword “bounds” (QXPScriptingAdditions.osax). I never heard about crashes, but only various malfunctions in existing applescripts (specially with the Finder).
→ Most probably you can see if QXPScriptingAdditions.osax is installed in the crash log…

Hi jj!

Thank you for your very good advice. You solved my problem. By deleting the file QXPScriptingAdditions.osax the application did not crash any longer.
I am very happy. This is a very strange problem.

Thank you jj! Greetings from Germany, hoschy07.