Make notebook arrows scroll the tab view
Arrows of the too-many-tabs-for-window-width state should behavior like arrows of menus, allowing auto-smooth-scrolling when the mouse is over it.
This is the same reported that was automatically closed at: https://bugzilla.gnome.org/show_bug.cgi?id=377441
It seems like an important usability problem to me. Hence, opening a new issue here.