Hi, Chris, thank you for report. Yet, mine is different. My case happens from time to time, not always, when I type in urlbar. Completions should appear below urlbar, but when completion pull-down flickers, about half of key types are swallowed into vacuum.
I've come up with better workaround: choose enter-exit, my favorite, as the global focus option, and let window matcher select enter-only for firefox. Since my ff is always fullscreen, it does not harm. Teika (Teika kazura)
