Firefox: keyboard shortcut for 'Highlight all' in find bar

In firefox, I can't find any keyboard shortcut for the 'highlight all' feature in the Find toolbar at the bottom of the FF window. Is there a keyboard shortcut, and if not, what is the easiest way to assign one?

Edit: The answer below is for Windows, for doing the same on Mac OSX, see this question.


ALT+a works fine for me to toggle the Highlight All feature when the Find toolbar is displayed.