int nMouseClickedOnce = 0;
int nMouseClickedTwice = 0;

void mouseClick()
{
   int nWaitTime = 200;
   if (nMouseClickedOnce == 0)
   {
      nMouseClickedOnce = 1;
   }
   else
   {
      nMouseClickedTwice = 1;
   }
   while(nWaitTime > 0)
   {
      nWaitTime -=1;
      wait(1);
   }
   nMouseClickedOnce = 0;
   nMouseClickedTwice = 0;
}

void test()
{
   on_mouse_left = mouseClick;
   if (nMouseClickedTwice)
   {
      printf("Mouse clicked twice");
   }
}