It's not possible to drag and drop:
- the folders at all
- the files to folder tree and [..] item
- the files while holding Ctrl+Shift or Alt to other app or desktop to create shortcut
- the files while holding Ctrl+Shift or Alt within XnView - file is copied instead
- multiple files (probably related with another known issue
XnViewMP Version 0.20 (Sep 25 2009), Windows Vista 32 bit SP2.