I seem to remember him saying before that the crazy extra button on his title bars moves windows between monitors (dual-monitor setup) or something like that.
I'm not sure if I'll use this new feature, but before I started using Firefox I didn't like the idea of tabbed browsing, but now I can't live without it... We shall see. If Patchou pulls it off smoothly then I will probably end up using it (and let's face it - how often does he fail to do things smoothly?
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)