USABLE RECT
Using file with the optional parameters, WINDOW_RECT or USABLE_RECT allows BR to distinguish between window dimensions and the useable area of windows.
file(nn,"WINDOW_RECT | USABLE_RECT", MAT num-arrayname)
The above file() reference redimensions num-arrayname to 4 elements and returns X (horizontal), Y (vertical), Width, and Height in pixels of either the window or usable area rectangle.