HRGN CreateRectRgn(
  int nLeftRect,   // x-coordinate of upper-left corner
  int nTopRect,    // y-coordinate of upper-left corner
  int nRightRect,  // x-coordinate of lower-right corner
  int nBottomRect  // y-coordinate of lower-right corner
);
 

 
DECLARE INTEGER CreateRectRgn IN gdi32;
    INTEGER nLeftRect,;
    INTEGER nTopRect,;
    INTEGER nRightRect,;
    INTEGER nBottomRect