I think, to reduce space usage and made Firefox more intuitive, you should go in direction Operating Systems went. It places some window buttons, like close or mute into popup menu or window tooltip (tooltip window with preview).
In my opinion close and mute buttons should be placed on tab preview button. You should also place here navigation buttons + url bar. Url address should be placed on bottom of window and should be semi-transparent. If mouse go at url address (bottom), it should go to top of browser (page) window. Why display url address in url bar and at bottom of window? Because we would display url bar on tooltip window, but it autohide, when mouse button aren’t on tab or on tooltip. I read you decide to always show url address of current tab.
Of course, preview window should be interactive and should disappear, when mouse isn’t at preview window or tab.
I think, url placed at bottom should be hidden when there’s no input to browser window. On mouse move, keyup/keydown, etc. we could display this text. Why? You decided to always display urlbar, because protect users against hijacking. If user doesn’t interact with page, so don’t send sensitive data, there’s no reason to display url bar. Of course, some page could display fake news, so there’s still little problem, but this problem is very seldom.
I have done first UI prototype: https://rapidshare.io/3yo/PasekAlaOS.tar.gz .
There’s still no URL addresses at bottom viewed, but I will try to address this. Problem is it could be hard to do without XUL.
My extension sources are under GNU/GPL v3.
Second prototype:
https://rapidshare.io/69U/PasekAlaOS_(1).tar.gz
Many parts now working. Still home button didn’t work, showing popup automatically on tab hovering don’t works (you must click button) and there’s need to made some other changes.
Third prototype:
https://rapidshare.io/8N3/PasekAlaOS_(2).tar.gz
URL overlay now shows at bottom/top. Home and refresh button now worked. I must still handle hide navigation bar and displaying my popup at certain place. Please, test my extension.
I have an similar idea now. Maybe move navigation buttons to tab panel and remove urlbar. Urlbar could been displayed only on new tab. Of course, I still think there’s should be url displayed on bottom/top of each tab, as described before.
In my opinion, many users newer use urlbar. Many only use it to go to google.com and them search. So hide it to new tab makes sense. User will simply open a new tab and type address/search criteria. When user decide to left page, he/she simply close tab. I don’t see reason, for normal users, to type url on other page (in urlbar, when viewing some page).