When properly set, applications will have a chance to automatically
detect HiDPI and act accordingly. This is the case for Fedora 23
template and GNOME apps (maybe even all built on top of GTK).
But for privacy reasons, don't provide real values, only some
approximate one. Give enough information to distinguish DPI above 150,
200 and 300. This is some compromise between privacy and HiDPI support.
QubesOS/qubes-issues#1951
This commit is migrated from gui-daemon repository
(dec462795d14a336bf27cc46948bbd592c307401).
