How to get the full path of the current highlight file in Directory Opus

I met some troubles when I wanna get the full path of the current selected file in Directory Opus.

When I called GetForegroundWindow Windows API, and the classname of this HWND is Directory Opus.
Then, how to get full path of the current selected file

Retrieving File and Folder Information is the interface for getting that information from outside of Opus.

thx , it helps.