Menus and popups don't appear on non-primary Xinerama screen

I have just switched over to Xinerama and upgraded to Qt 4.6.1 but this bug remains. Menu and combobox popups do not appear on the second (right-hand) monitor with Xinerama enabled.

If the window is placed between the two monitors such that more than half of the control is on the primary monitor then the popup will appear entirely on the primary monitor, but if more than half of the control is on the secondary monitor then the popup will not appear at all. It does however successfully grab the cursor and requires a click to make the "invisible menu" go away.

Interestingly enough with "qtconfig" I can still use keyboard shortcuts on the secondary screen even though the menu is invisible, however while pressing Alt+H,A works on the primary screen to open the About window, on the secondary screen the About window doesn't appear either. But since it's a modal dialog it blocks access to the rest of the application so I have to kill the whole app and restart it.

According to xprop, on the primary screen it looks like this:

WM_NORMAL_HINTS(WM_SIZE_HINTS):
user specified size: 388 by 143
program specified size: 388 by 143
program specified minimum size: 388 by 143
program specified maximum size: 388 by 143
window gravity: NorthWest

And on the secondary screen the same window looks like this:

WM_NORMAL_HINTS(WM_SIZE_HINTS):
user specified size: 0 by 156
program specified size: 0 by 156
program specified minimum size: 0 by 156
program specified maximum size: 0 by 156
window gravity: NorthWest