WIP: BUGFIX: 389448 Factor in devicePixelRatio in setWindowGeometry

This commit is meant to fix the hidpi bug that causes windows to only take up one quarter of the screen, by scaling the calculated geometry from device-independent pixels to physical pixels before setting the window geometry.

Note: I only really tested this on my own (single) high-dpi display, at a scaling factor of 2. I don't know how well it works on multiple desktop configurations, or mixed DPI setups.