@Pilou
Well you lost 20pix, and win lot of surface with every tab.
Vertical text is readable, only Modeling give some trouble, because the word contains many letters that work in both side I guess ... (M=W ?).

A bit off topic, but I think it would be nice to have some constancy in colors code, between what is selected, or not.
Like having the same color for selected suface/curve in the viewport, and selected/active tab (I still have the filling the actual desaturated blue is not eye catching enough ... I often miss click the tab I want to switch to ...)



(that's having said, I'm not sure about the object surface color :S)