[Qt-interest] weird event loop hang with Qt Mac 64-bit Cocoa and QStackedLayout?

[Paul Miller]

On 12/29/2010 4:28 PM, Paul Miller wrote:
> I'm at a loss here - have two applications that have QStackedLayouts in
> them. Built with Qt 4.7 (64 bit) Cocoa (also tried with 4.6, same
> results) - works fine on my machine(s).
>
> Sent to a user with no dev tools/Qt installed. On his machine, most of
> the time, after switching the current widget his program will just hang
> for about 10-15 seconds. He sent me a sample report and most of the time
> is just waiting in the kernel message trap. After awhile, the program
> continues on normally.
>
> I've never been able to repro this.
>
> Program rebuilt with 32 bit CARBON version of Qt works FINE.
>
> Anyone heard of anything like this? I'm totally STUMPED.

More on this. I learned that this only happens when the parent is a 
QDialog. If I reparent everything under a QMainWindow then all works 
normally.