Dropdown menu appears on other monitor in multi-monitor setups

[lassoan]

Some dropdown menus (e.g. for recent modules, layouts, crosshair, but NOT the Modules selector) spawn on a different screen than is occupied by the Slicer application. The screenshot below shows an example with the layout menu. The screenshot bridges an external monitor (upper, where the Slicer window is) and my laptop screen (lower, where the layout menu appears). The top of the layout menu is at the top of my laptop screen.

If I move the Slicer application window to my laptop screen, all the dropdown menus appear in their proper places.

This problem was not present in the prior preview release I used, 2020-05-27. It is also not present in any of the module UI dropdowns (built-in or ones I’ve added with QComboBox or qMRMLNodeComboBoxes). So far, I have only seen it occur with dropdowns from the Slicer Toolbar. It happens for all of those except the module selector (the one which shows the currently selected module).

Both screens are high resolution (laptop is 3840x2160 and external monitor is 3440x1440).

Full information: https://discourse.slicer.org/t/dropdown-menus-spawn-on-other-monitor/13003

[lassoan]

It seems to be a bug in Qt-5.15.0:

https://bugreports.qt.io/browse/QTBUG-85012

[jamesobutler]

They closed the previous bug report as a duplicate came in. The new one is https://bugreports.qt.io/browse/QTBUG-86067 which anyone can vote on.

[jamesobutler]

A bug fix commit was evidently issued June 10th which will be included in Qt 5.15.1. Also a changes file for Qt 5.15.1 was commited which seems to indicate that the Qt 5.15.1 release is imminent.