Return
codes.
This function returns an integer (lInside) indicating whether the rectangle
is inside the region:
RRGN_ERROR
RRGN_INSIDE
RRGN_PARTIAL
RRGN_OUTSIDE
Possible
Errors Detected: When an error is detected, the handling routine must
call WinSetErrorInfo to post the condition. Error codes for conditions that
the handling routine is expected to check include:
Refer to the "Error
Explanations" section in the Presentation Manager Programming Reference
for further explanation.