2 messages of getting all opened file names from Notepad++ is available :
WM_NBOPENFILES and WM_GETOPENFILENAMES
To get the opened file names from Npp, you have :
1. send the message WM_NBOPENFILES to get numbers of opened files.
2. allocate the buffer to get the file names.
3. send the message WM_GETOPENFILENAMES to get the file names.
4. don't forget to deallocate the buffer.
You can find the demo in Insert plugin (code source) here :
To test your development, you will need notepad++ binary which supports these 2 messages :
I'll make the newest source on cvs service as soon as possible.
I just comited the changed source on CVS.