Review Request: [Quicklaunch] Refactoring, layout fixes and a drag & drop marker.

[Ingomar Wesp]

Sorry for the form of this reply (I'm writing this from my phone)...

! And I noticed that multiple row support is gone at the moment it seems :/

Multiple row support should work (unless you ran into a bug), but new rows are created only when there is enough space to fit the user-configurable icon size for each row. For an icon size of 32px, this means that the height of the panel needs to be at  least 64px for two rows to be shown.