Draging a file into a running copy/move dialog will cause the file to be copied
to the same destination as the other file(s) already beeing copied.

Let's say I'm browsing a cd or a folder on a samba connection. There's a lot of
mp3's there, but I just want to copy some of them. I drag one file over to a
local folder, either using the spatial mode or just dropping it on one of the
bookmarks in the sidebar. Then, I look around further in the folder and find
another file I want, dragging this onto the already opened copy dialog, will
cause the new file to be copied after the first. Hence, I don't have to have two
copy dialogs and two connections open at the same time. This will be particulary
practical for cdroms, who would have to seek to two different places at the same
time.