INT 62 u - FGDRIVER v1.10 - "FG_MOUSEBUT" - GET MOUSE BUTTON PRESS/RELEASE CNTS
        AX = 007Ch
        CX = mouse button (1 = left press, 2 = right press, 3 = middle press,
                          -1=left release, -2=right release, -3=middle release)
        ES:BX -> variable pointer record (see below)
Return: variables updated
Note:   returns the count of presses or releases since the last call to this
          function; if the count is zero, row and col will also be zero
SeeAlso: INT 33/AX=0005h,INT 33/AX=0006h

Format of variable pointer record:
Offset  Size    Description
 00h    WORD    segment of WORD buffer for press/release count
 02h    WORD    offset of WORD buffer for press/release count
 04h    WORD    segment of WORD buffer for screen space col of last press/rls
 06h    WORD    offset of WORD buffer for screen space col of last press/rels
 08h    WORD    segment of WORD buffer for screen space row of last press/rls
 0Ah    WORD    offset of WORD buffer for screen space row of last press/rls