Windows 8 seems to have some security on Dragging and Dropping within or between programs. For instance, I used to be able to drag and drop into VideoLAN, music and video files. But I can'[t do that from within Windows 8.
I also used to be able to drag an MP3 or Video or even an ePub iBook file right into iTunes, and I can't do that anymore either. Or apps or anything else. I CAN however still right click on the files and open them WITH VLC or iTunes.
I used to be able to open all kinds of files in various programs in XP and even Windows 7. But 8 does not allow it, I don't know if it s blocked. I appears to me that I can still drag and drop into those programs in Windows 7.
This may be due to the extra security which is on files that exist in the Program Files folder. You can't just drag and drop freely into that folder any longer. There are several Programs I have that I drag into Program Files and then create a desktop shortcut for, and I am always asked for permission now, where I never had to in XP/Vista/7.