I think you want a music pause/play function,
here is an example :

Code:

---

var mediaHandle;
var isPlaying = on;

panel crtlPanel
{
   pos_x = 0;
   pos_y = 0;
   layer = 1;
   button = 0,0,<pauseOn.bmp>,<pauseOff.bmp>,<pauseOn.bmp>,musicOnOff,null,null;
   flags = visible;
}

function musicOnOff()
{
   if (isPlaying == on)
   {
      isPlaying = off;
      media_start(mediaHandle); // if you want to start it all over again,
   } else {                     // change it to media_play
      isPlaying = on;
      media_pause(mediaHandle);
   }
}

function main()
{
  level_load(yourLevel);
  wait(2);

  mouse_mode = 1;
  media_play("yourMusic.wav",null,1000);  // adjust the vol. (1000)
  mediaHandle = media_handle;

  while(1)
  {
    mouse_pos.x = pointer.x;
    mouse_pos.y = pointer.y;
    wait(1);
  }
}

---

Use your own bmp and media file off course.