Multiple Windows

I have seen plenty of examples of people having the game display span multiple screens, but this is not what I want. I'd like to stick with seeing the world around me on my primary screen. I would like to, however, be able to put my map, inventory, battle log, etc. on a second screen. To do this now, I'd have to also extend the display of the world onto that second screen. This would be very problematic since a) it would not be properly centered at all with two rather than three screens and b) it would cost much more to render since my primary screen alone is 2560 x 1600 with nearly maximum settings.

I'd like to have a second window that only renders UI elements like chat boxes and maps but nothing 3D and be able to freely move UI components between the two windows.

Alternatively, a lazier way of accomplishing this would be to at least let us define what portion of the "window" renders the 3D world rather than just assuming we want to use the entire window. That way, I could have a really wide window spanning both screens but not have the center of my display in between two monitors.