Missing Selection Mode in TabBar
Sometimes you want to select multiple tabs, to close them or put them in another window. (Firefox support this too) The design would be: You has selection mode for example with the button in the header bar activated. If you then click on a tab(not only one little checkbox), the tab is highlighted (blue) and a filled checkbox appear where the logo was. Maybe it should before appear there too, but clear.
Also I would prefer to have like at the "Notebook" a (blue) stripe under the tab.