an example can be found on AMOSPro_Examples:Examples/H-5/Help_50.AMOS
Reads the status of the MOUSE buttons, and tells you the result in the form of a bit-pattern.
Bit 0: Set to one if the left button has been pressed. Normally zero.
Bit 1: If the Right button has ben pressed, you'll get a one in this
position. Otherwise, zero.