Unless I am misunderstanding what you are asking for, you should be able to do this using "User Defined Areas".
I think that if you tick "Allow cursor to return freely to (and within) the primary working area" on the Curosr->Sticky options page, you will have the functionality that you are after. If not, please let me know.
DMT v2.11 has just been released with the above mentioned support.
DMT v2.11 has now been released which has a new option "Change Wallpaper periodically" -> "But not if running full screen game or presentation" which if checked will stop the wallpaper changing while running full screen games.
DMT v2.11 has now been released which I hope fixes these issues
Missing history update for web site for v2.11
v2.11
Fix for start up of hooks thread