Its really bad design to make the whole page move away when you open the notifications/friend/search tab. Might be only me, but I consider that quite annoying when text is moved around like that, instead the corresponding tab should blend over the rest of the page I just checked it on mobile, on the mobile version you actually blend the tab over the remaining page. This is how it should be on the desktop version too. The performance on mobile is horrible now though (not that is was any good before....)