mouse_port = MM.INFO(OPTION MOUSE)
 IF mouse_port > -1 THEN ' we have a mouse
   CONTROLLER MOUSE OPEN mouse_port
 ENDIF

mport = mm.info(option mouse) + 1
if mport then
 controller mouse open mport-1, LeftClick
 gui cursor on 2
 settick 50, PeriodInt   ' periodic interrupt to move mouse pointer
else    ' no mouse set so try find one
 mport = 4
 do
   on error skip
   controller mouse open mport-1, LeftClick
   if MM.ERRNO then
     mport = mport - 1
   else
     gui cursor on 2
     settick 50, PeriodInt   ' periodic interrupt to move mouse pointer
     exit do
   endif
 loop until mport = 0  ' no mouse found anywhere
endif

SUB SEinitMouse
 'try to find mouse and set MOU.SE to it's port

 LOCAL INTEGER i
 IF MM.INFO(VERSION) >= 5.07 THEN
   MOU.SE = MM.INFO(OPTION MOUSE)
   ON ERROR SKIP
   CONTROLLER MOUSE OPEN MOU.SE
   IF MM.ERRNO <> 0 THEN
     MOU.SE = -1
   ENDIF
 ELSE
   MOU.SE = -1
 ENDIF
 FOR i = 1 TO 3
   IF MOU.SE < 0 THEN
     ON ERROR SKIP
     CONTROLLER MOUSE OPEN i
     IF MM.ERRNO = 0 THEN
       MOU.SE = i
     ENDIF
   ENDIF
   IF MOU.SE >= 0 THEN
     IF TUIquestion("MOUSE TEST", "Mouse found on port " + STR$(MOU.SE) + ", use it?") THEN
       LOAD PNG "Mouse.PNG", 640, 50
       GUI CURSOR ON 0, MOUSE(X, MOU.SE), MOUSE(Y, MOU.SE), RGB(GREEN)
     ELSE
       MOU.SE = -1
     ENDIF
     EXIT SUB
   ENDIF
 NEXT i
END SUB

IF MM.INFO(VERSION) >= 5.07 THEN
  MOU.SE = MM.INFO(OPTION MOUSE)
  ON ERROR SKIP
  CONTROLLER MOUSE OPEN MOU.SE
  IF MM.ERRNO <> 0 THEN
    MOU.SE = -1
  ENDIF
ELSE
  MOU.SE = -1
ENDIF
...
IF MOU.SE >= 0 THEN ...

 LOCAL INTEGER x = MOUSE(X. MOU.SE), y = MOUSE(Y. MOU.SE)
 LOCAL INTEGER l = MOUSE(L. MOU.SE), r = MOUSE(R. MOU.SE), w = MOUSE(W. MOU.SE)

 LOCAL INTEGER x = MOUSE(X, MOU.SE), y = MOUSE(Y, MOU.SE)
 LOCAL INTEGER l = MOUSE(L, MOU.SE), r = MOUSE(R, MOU.SE), w = MOUSE(W, MOU.SE)