Add a Non-Interactive window level

Awhile back, the Background window level was changed so that the window would be interactive, even if it was set to be in the background.  Some users would like the window to not be interactive.  Look into adding a 4th window level called "Non-Interactive" to allow this functionality.

Relevant commit:  https://github.com/mikepj/XRG/commit/c810ee66cc95dd7223812268e870f0c55ebc35a4