[CentOS] Independent dual monitors on CentOS 7

Does anyone have the magic incantation required to getting 
*independent* multi-monitors going under CentOS 7?   Ideally
under xfce or trinity, but I'm interested about GNOME/KDE
observations as well.

I'm trying to move my main workstation from CentOS5 to CentOS7
and while the spanned desktop works, not having independent 
monitors really cuts into my productivity.  i.e.:  I couldn't
care less about dragging things from one screen to another, but
not having a 3x3 virtual desktop grid on each monitor independently 
really sucks.

Devin