INT 33,5 - Get Mouse Button Press Information

	AX = 5
	BX = 0	left button
	     1	right button


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

		│F-8│7│6│5│4│3│2│1│0│  Button Status
		  │  │ │ │ │ │ │ │ └──── left button (1 = pressed)
		  │  │ │ │ │ │ │ └───── right button (1 = pressed)
		  └──┴─┴─┴─┴─┴─┴────── unused