Add support for opacity lock (patch from Darren Salt <linux@youmustbejoking.demon.co.uk>, bug #1958), add support for changing opacity using mouse button 6 and 7 (patch from Darren Salt <linux@youmustbejoking.demon.co.uk>, bug #1959), add move/resize cancellation using a configurable keyboard shortcut (patch from Darren Salt <linux@youmustbejoking.demon.co.uk>, bug #1963), optimization for the compositor rebuilding screen when settings change (me :)

(Old svn revision: 22213)