Too many properties are still of type String

I think you are being a little harsh (especially after reading your other recent post).  As you noted, it was a complete rewrite and, honestly, string values for those two properties satisfy most of the users.  Maybe there is even a reason why it had to stay string (e.g. ensure proper theme rendering or to provide titles in floating window)?  I also assume you are a software developer and know that we sometimes make compromises to ship a product.  Other times we don't see something that is obvious to one person because our focus was on something much more complicated.  The new docking product is a huge improvement over the previous version.  This isn't the last revision of the docking product.  If it doesn't fully meet your needs today, there are nicer ways to request an enhancement.

Hi Markus,

The title is used many places throughout the UI and does need to be a string (especially for UIA, etc.).  That being said, we are open to adding Header-like functionality again if it makes sense to do so.  The way Header was before though, it was the same in all locations and with our newer contextual content templates, you can change appearances based on usage location.  Keep in mind though that it's much easier in general to customize tab appearance now in 2016.1.  If you can go into detail about your specific needs and maybe include a mockup screenshot of what you want to do that isn't easy right now, please send that info over and we'll be happy to discuss.

As for Description, that only shows on the switcher so we could probably make that into an object.  Would you like a DescriptionTemplate property too?

Currently I'm fine -- the several contextual content templates are definitely a good solution (they would be even better if a generic pure View-View Binding back to the DockingWindow would be possible [using RelativeSource with AncestorType]).