GTK+ doesn't support shading of client-side decorated windows, and likely
never will (not least because shading is conceptually questionable if the
app customizes the titlebar), and neither do other CSD implementations like
Chromium's. A shortcut that only works with a decreasing number of windows
is more confusing than helpful, so don't expose it.
https://bugzilla.gnome.org/show_bug.cgi?id=645460
intltool is unmaintained nowadays while upstream gettext gained
support for formats like GSettings schemas and .desktop files,
and offers a mechanism to teach it about other XML formats not
yet supported out of the box which we can use for the rest.
So there's nothing stopping us, just make the switch ...
https://bugzilla.gnome.org/show_bug.cgi?id=769073
