DW      PATBAR          ; fill rectangle (X1,Y1), (X2,Y2)

  Input:
     AX         X1--the rectangle's left coordinate
     BX         Y1--the rectangle's top coordinate
     CX         X2--the rectangle's right coordinate
     DX         Y2--the rectangle's bottom coordinate

  Return:
     Nothing

Fill (but don't outline) the indicated rectangle with the current fill
pattern and fill color.