INT 33,6 - Get Mouse Button Release Information

	AX = 6
	BX = 0	left button
	     1	right button


	on return:
	BX = count of button releases (0-32767), set to zero after call
	CX = horizontal position at last release
	DX = vertical position at last release
	AX = status

		|F-8|7|6|5|4|3|2|1|0|  Button status
		  |  | | | | | | | `---- left button (1 = pressed)
		  |  | | | | | | `----- right button (1 = pressed)
		  `------------------- unused