INT 33 - MS MOUSE - RETURN BUTTON RELEASE DATA

         AX = 0006h

         BX = button

             0 left

             1 right

 Return: AX = button states

             bit 0 left button pressed if 1

             bit 1 right button pressed if 1

         BX = number of times specified button has been released since last
              call

         CX = column at time specified button was last released

         DX = row at time specified button was last released

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