There was a wish once upon a time to make the section buttons in Lancelot smaller, that is narrower, because people thought that they waste too much space.
At first, I was reluctant since I didn’t see the point in doing it, but I changed my mind recently - Lancelot is pretty much feature-complete as it is (at least from my point of use/view), so I decided to implement something that I absolutely have no use for, but somebody else will. The fact that I’m missing the vertical tabs in Amarok could be another reason in making this :)
So, if you want to have the buttons as shown in the following image, just right-click them and choose the appropriate* option. (mind that this is available in trunk, not in the KDE SC 4.4).
*It says ‘toggle collapsed sections’ at the moment, but I’ll change it as soon as I think of a better name.