How do I get filename/file extension of a file on the Desktop in win7 which I drag?

I'm working on a project which is a tiny tool running in the background. It only has a tas开发者_JS百科kbar icon most of the time.

And it will record user mouse activities on the desktop(which is explorer.exe). Now I can get desktop mouse activities by making a DLL using c++ and use setWindowsHookEx() to set a global hook.

Question is, when people drag desktop icons and files on the desktop, when they dragging, how can I get the filename and extension of the file they are dragging?