This changes how the media-keys manager determines successful
key-bindings from KeyRelease to KeyPress so that it does not conflict
with third-party applications that want to use modifier keys as global
key-bindings. We've already done this change for general keybindings and
marco.

(port of d0368790c6deda728eb46337247bd0a9a844ac4b without deprecations fixes to 1.18 branch)

This allows mate-settings-daemon to honor global keybindings whenever
a different application has keybindings that seem conflicting, but are
usually not.

For example, an application defining a `Super_L` keybinding
and MATE having defining a shortcut that uses the `<Mod4>` key. They are
the same physical keyboard, but one is a modifier and the other is not.
Without requesting keyboard reports from other windows, the `<Mod4>`
shortcuts are swallowed whenever there is a `Super_L` shortcut
elsewhere.

(squashed cf0b97690c9d8606be4e07b58a4cf7070b53570d + 603e331e6cf480d2f9aed1e7d096333df39215aa for 1.18 branch)

This menu was not noticed back in 2015 when support for custom panel menu themes was added

This reduce the width of the dialog

Applications might want to establish keyboard grabs on button presses so we
should also ungrab the keyboard when a button press occurs after the locate
pointer key is pressed.

https://bugzilla.gnome.org/show_bug.cgi?id=125618

and revert "GTK 3.21: Fix background changing, startup delay".
These are no longer of need as Caja reclaimed its ability to draw backgrounds.

my stupid mistake - it was applied to the first device in the list only