Cannot drag tags to top level 'None'

[Dougie Nisbet <dougie highmoor co uk>]

1. We need an UNDO!

2. While trying to search on multiple tags by dragging them individually 
to the search bar (ORing them) I found that there was insufficient room 
on the find bar and could not see a way of adding further tags. So I 
tried selecting multiple tags using the Ctrl key, BUT, while trying to 
drag the multiple selection to the find bar my mouse slipped and I 
accidentally moved all these tags to be a sub-tag of another tag. With 
them all selected, I would, ideally, have clicked on UNDO, but as that's 
not possible, drag them all back to the Top Level. But I can't do that, 
Can I? Presumably I want them all to be a sub-tag of (None).?

3. Must remember and backup my photos.db file before every run of f-spot!