Retrieves the dimensions of the tightest bounding rectangle around the current clipping boundary.
The clipping region's type. It can be any of the following values:
COMPLEXREGION Clipping region has overlapping borders.
ERROR Device context is not valid.
NULLREGION Clipping region is empty.
SIMPLEREGION Clipping region has no overlapping borders.
The dimensions are copied to the buffer pointed to by lpRect.