1. Load attached test case.
2. Tab so that focus is on one of the buttons.
3. Perform a mouse click on the same button. (Notice focus ring disappears.)
4. Press Tab again. (focus has been lost and resets to the beginning of the document)
Note: It's probably okay to "hide" the focus pseudo-state when switching to a mouse, but Tabbing should cause focus to come back to the same element rather than losing document.activeElement entirely.
Created attachment 194349 [details]
test case demonstrating bug
See expected behavior in Firefox 19 for Mac.
See also: bug 22261.
Any updates on this? I see that there's not been any changes since the bug was reported 5 years ago. This issue makes building custom widget with focus management very tricky.