Added option to hide empty notification tray.
Replaced tab indentation with 4 space.
add missing screenshot keybindings
add missing screenshot clipboard keybindings
Add option to show/hide desktop icons altogether

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Add option to modify the alt-tab switcher delay

The alt-tab switcher uses a default delay of 150 ms before actually
showing the dialog to avoid repeated flashing. The downside of this
approach is that it makes it appear to be laggy. This commit adds the
ability to modify the delay of the dialog in the Window settings with
150 ms remaining the default choice to maintain the previous behavior
for people who prefer it.

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Adds code that will sort the icons in cinnamon-settings by their display
name.
Add about dialog to applets and desklets
sound applet: hidpi support for cover art
sound applet: Add a separator between the player status and track info.
st-label.c: Prevent .xsession-errors overflow - a common error/oversight
when using timers that update a label occasionally, is forgetting to
disconnect these timers when the widgets they act on go away or are
replaced by a duplicate new object.

When this happens, you can get a cumulative increase in log spam as these
timers add up, and continue to try to act on bad objects.

This doesn't do anything to prevent this bad behavior, but it will squelch
the log messages to one time only per StLabel instance, and provide a bit
of debugging information so these errors can be fixed.
st: A couple cleanup fixes
Looking glass: Use Melange (gtk) by default.  Port usage over to the new program,
while keeping api consistent.  Added default hotkey for toggling looking glass on
and off.  Gtk looking glass runs as an on-demand dbus service.
Fix error in previous commit
Merge pull request #3172 from StealthOfKing/notification-applet-hide

[2.4] Added option to hide empty notification tray.
cinnamon-settings: Be more clear about disabling the 'special windows modifier'
key'.
menu applet: get rid of old transients
sound applet:  Fix a warning, and improve track position accuracy:

- timeout_add_seconds isn't 100% accurate, but instead of switching to
  timeout_add (ms), we can keep what we have currently, and occasionally
  re-sync the position from the player itself.  It's still imperfect,
  but it won't require additional processing resources, and at worst
  it should only ever be 1 second off.
sound applet: Hide parent, not the seek slider actor, when disabling seek
popupMenu.js: Filter out button-release events while a popup is opening,
to avoid unintentional selection of popup items due to busy event handling.

Fixes #3294
Fixes #3331
Fixes #3116
Fixes #3221