Picker coordinates scaled wrongly on Mac (MacOS 11.2.3) with a Retina display when embedding in Qt
#17049 (closed) reported an issue on OSX 10.12 where the picker coordinates are off by a factor of 2, when using a Retina display. The behaviour only occured when embedded in Qt. A fix was implemented in !4201 (merged).
However, on MacOS 11.2.3 the picker coordinates are again off by a factor of 2 on a Retina display when embedded in Qt, but in the opposite direction to the behaviour reported in #17049 (closed) (i.e. the returned coordinates are twice what they should be; in the original issue they were half what they should be).
The issue is resolved if the changes in !4201 (merged) are reverted.
I suspect that changes in MacOS or Qt to better handle high DPI screens render the fix in !4201 (merged) unnecessary. However, reverting !4201 (merged) may have unintended consequences for other platforms (e.g. 4k displays on Windows).
Attached are the two example apps from #17049 (closed). vtk_bug.py does not have the issue, while vtk_bug_qt.py (embedded in Qt) does have the issue.
Tested using PyQt5 version 5.15.3 and VTK version 9.0.1.