[RESOLVED] Open multiple custom associated file to a single-instance application (from explorer)

My app is a single-instance MDI application which opens multiple documents (via file menu/command line) in MDI child windows.
I have associated my own filetype in explorer.
Now, I want, if I double click associated files on explorer, the files will be opened in the active instance of my app (in child windows).

Basically I need to pass the file path to the active instance of my application.

I have an idea for this. But that is too complex. (Creating mutex to find previous instance and passing filename with WM_COPYDATA etc. :eek:)

Anyone got simpler idea ? OR correct google keywords ? (my search didn't result good results)