Fix PopupBox misalignment on mixed DPI systems #3641
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PopupBox correctly transforms from device coordinates using the PresentationSource transform matrix, but then uses the global system DPI to transform back to device coordinates. This causes placement issues on systems with multiple DPI/scaling settings.
Keboo added bug release notes 
Keboo approved these changes Aug 7, 2024
This was referenced Sep 26, 2025
This was referenced Oct 6, 2025
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PopupBoxcorrectly transforms from device coordinates using thePresentationSourcetransform matrix, but then uses the global system DPI to transform back to device coordinates. This causes placement issues on systems with multiple DPI/scaling settings.These examples were captured on a system with mixed scaling of 100% on the primary screen and 225% on the secondary, with the demo app placed on the latter.
Before:
After:
I chose
BottomAndAlignRightEdgesbecause the misalignment is particularly noticeable, but ultimately every placement mode is misaligned.