Doubleclick causes multiple start of my application

When I Doubleclick on a file my application starts as it should be. But if i doubleclick another file my application starts a second time ... ??
how can i avoid this ??
I would be very glad to get some ideas of u.
Thanks a lot,
Marko

Maybe you should look at the code of Pview.

When your application starts you look if the process already exists. If yes, your application exits.

Yo may read Microsoft Knowledge Base, Article ID Q109175 (16 bits) and Q141752 (32 bits). You will find an example showing how to enable only one instance of your application at a time.
In fact, you have to change InitApplication(), InitInstance() and ExitInstance() of your App Class to register your application and then verify if your application isn't already registered.

Thanks a lot for your posting, they got me very close to the solution of my problem !!
Now my application starts only one time but how do I let my program know, that it has to load new data, if i double clicked on a file in the explorer ??
Do u have any idea ?
Marko