standalone - start only once

[Nicolas Cueto]

Hello list,

Is there a way of preventing a standalone from 
being started again once it has already been 
started?

A backdrop might be a solution, but perhaps 
there are other Rev options?

The reason I ask is that very young users of my 
stacks will click a standalone's icon again and again
if the start-up screen does not appear *immediately* 
(or, sometimes, they just like to click because it's fun).

Thank you.

--
Nicolas Cueto