Gah! How do I make my window stop jiggling? Firefox, Vista

Windows Vista, Firefox, Google as homepage (not that that signifies, but).

My normal Firefox homepage setup shows Google as one tab over on the left. If I want more tabs, I right-click on the first Google tab and select “Open New Tab”.

Last night, in a fit of tiredness, I right-clicked and selected “Open All In Tabs”, which wasn’t what I wanted. It gave me a second toolbar below the normal toolbar that usually has the tabs in it, and it had tabs open in it. The first, topmost, toolbar, now had no tab, but just said “Google”.

So in a further fit of tiredness, I right-clicked on this topmost toolbar that only said Google with no tabs, to see what it said, and :smack: chose “Delete”. So the topmost toolbar obligingly went away, leaving a blank gray space, and underneath it is the toolbar I am now using.

Which is jiggling. Up and down.

I have tried uninstalling and reinstalling Firefox, which didn’t work.

I have tried going back to a System Restore point, which didn’t work.

It comes and goes randomly; sometimes when I open something from Bookmarks, the website does not jiggle. And then when I open a new tab, sometimes it jiggles and sometimes it doesn’t. Sometimes when I close a tab, the jiggle goes away for the other tabs, and sometimes it doesn’t. Sometimes when I click on Preview here, the Preview jiggles, and sometimes it doesn’t. And when Preview here is jiggling, if I go to a tab that is jiggling, and come back here, the Preview window will be jiggling.

Clearly, Firefox is being deeply conflicted by my deleting that topmost toolbar, or whatever it was I did. So how do I get it back?