This enables HiDPI support for GTK+ on Windows, so that the
fonts and window look better on HiDPI displays. Notes for the current
work:
-The DPI awareness enabling can be disabled if and only if an application
manifest is not embedded in the app to enable DPI awareness AND a user
compatibility setting is not set to limit DPI awareness for the app, via
the envvar GDK_WIN32_DISABLE_HIDPI. The app manifest/user setting for
DPI awareness will always win against the envvar, and so the HiDPI items
will be always setup in such scenarios, unless DPI awareness is disabled.
-Both automatic detection for the scaling factor and setting the scale
factor using the GDK_SCALE envvar are supported, where the envvar takes
precedence, which will therefore disable automatic scaling when
resolution changes.
-I am unable to test the wintab items because I don't have such devices
around.
https://bugzilla.gnome.org/show_bug.cgi?id=768081
4add92a431