"window-scale" is 1.0 by default; however, x11 implicitly set that to
2.0 on hidpi screens. This made the default 2.0, which was inconsistent
with the option. The "window-scale" property jumped from 1.0 to 2.0 when
a window was created.
Avoid this by factoring the DPI into the window-scale. This makes the
UNFS_WINDOW_SIZE return a virtual size; since this value is used for the
window-scale property only, this is fine and has no further
consequences. (Originally, this was possibly meant to be used for other
purposes, but I'm perfectly fine with redoing this again should that
ever happen.)
This changes user-visible behavior, and it's as if setting window-scale
multiplies its argument by 2 suddenly. Hopefully no user will get angry.
9800855895