Indicator is a bare layered click-through native window,
painted completely by GDK, including animation.
This commit also isolates some of the more spam-ish debug logging
under ifdef.
This commit also changes the system metric used for maximal window
height for the snapping purposes. Turns out, SM_CYMAXTRACK is way
too large, use SM_CYVIRTUALSCREEN instead.
https://bugzilla.gnome.org/show_bug.cgi?id=763013