Not sure what's wrong here, but the new file system view behaves differently on WIndows 7.

1) Click folder x
2) Hold SHIFT and select another folder
3) Release shift
4) should be able to click again and drag that selection to unmatched files.

However as soon as you click again, everything becomes de-selected and you are only dragging a single folder.

The workaround is to hold SHIFT again before step 4 and then you can drag (it's definitely a different mechanism though, as it shows the Windows-style transparent overlay of all of the files, as if you were doing a native Explorer drag).

The behaviour is inconsistent with both Picard 1.0 and normal Windows drag+drop semantics.