how to keep one instance???

[BruceKL WhoH]

I'm using wxWidget to build an editor, so I need a cross-platform solution (at least it should work on windows & Linux). 

Yes,it does work ,if you use a file to lock. But I want the app behave like this :
user click a .txt file, the the app runs and open the file, and later,if user click the same .txt file again, the app can detect the first app instance, and destruct, and popup the first instance to show the same .txt file.

For example,you can not open the same .doc file in two MS Word windows.

So, how can we get it ?

Thanks.
				 
　　　　　　　　BruceKL WhoH
　　　　　　　　BruceWhoHKL at gawab.com
　　　　　　　　　　2004-05-21