link between standalone and doc on windows

[Jeanpaulpoccard at aol.com]

My standalone creates its own docs which extension is ".hti"

On MacOS 
   no problem,

On windows
   The problem arises when I try to display sevral docs by doublecliking on   
their icon from the desktop.


A double click on a doc icon lauches the standalone and a doc window is 
displayed.
but   what   happens if I doubleclick on another doc icon   ?
I expect   the standalone to display a second doc window.
In facts, Windows lauches once more the standalone, and the two standalones 
coexist in the memory. 
How can I obtain on windows the same behavior as on MacOs, only one 
standalone managing any doc opened from the desktop ?
Thank you for your help
Cordialement
Jean-Paul