Futurebasic/Language/Reference/mouse

Description
If your program does not do any kind of event-trapping using the statement, then you can use the   function to determine whether the mouse button is currently down. In these circumstances,  returns  is the button is down, or   otherwise.

The  function will not work if your program traps events using. Since most well-designed programs trap events this way, the  function is probably of limited usefulness. See the functions to learn how to respond to mouse clicks using event trapping.

Note: You can also use the Toolbox function  to determine whether the mouse is currently down. works regardless of whether your program uses event trapping.