Got it, thanks. Element selection is bothering me now =) Your hint about it being slower than calculation was right and sent me on a journey of poking around with element detection and reorganizing the whole thing. Expanding to element is slow, but does wonders with low amount of shells, say we have million polys unwrapped…
No, that's not it. It's being able to select an element in the UV window and have the corresponding element highlighted on the 3D object. If I click a vertex on my UV, it should highlight the same vertex in 3D view.