Use MultiBar instead of Tabs...

A little bit amazing: I didn't even realize at first that I changed back
to using "Tab"-Containers instead of "MultiBar"-Containers. I was simply
missing the tool bar integration.

Well, then i saw that little thingie in the top left corner (color
gradient was wrong), when it suddenly came to mind: I wrote about 2,5k
lines of code to fix that one :-)