Windows WM handles AeroSnap for normal windows on keydown. We did this
on keyup only because we do not get a keydown message, even if Windows WM
does nothing with a combination. However, in some specific cases it DOES
do something - and we have no way to detect that. Specifically, winkey+downarrow
causes maximized window to be restored by WM, and GDK fails to detect that. Then
GDK gets a keyup message, figures that winkey+downarrow was pressed and released,
and handles the combination - by minimizing the window.
To overcome this, install a low-level keyboard hook (high-level ones have
the same problem as normal message loop - they don't get messages when
Windows WM handles combinations) and use it to detect interesting key combinations
before Windows WM has a chance to block them from being processed.
Once an interesting combination is detected, post a message to the window, which
will be handled in due order.
It should be noted that this code handles key repetitions in a very crude manner.
The downside is that AeroSnap will not work if hook installation function call fails.
Also, this is a global hook, and if the hook procedure does something wrong, bad things
can happen.
https://bugzilla.gnome.org/show_bug.cgi?id=776031
eece8a7dd2