main: allow use of 128px icons for the app switcher
http://bugs.activestate.com/show_bug.cgi?id=96084

The compiz app switcher on Linux can use 128px icons when showing icon
only.  This improves alt-tab appearance in that case.

(integrated from komodo (trunk) change 81065 by marky)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@13283 b87d16e7-d29f-4ee1-b5ec-817d645d335f