A: 

Similar to how you would do it on the web, you can just put the tab control and floating control inside a Grid and set the margins of the floating control to get it in the right spot. You could also use a Canvas element to contain the Grid and floating control and set the Canvas.Left and Canvas.Top.

You might need to dynamically measure the width of each tab, if the tabs are not determined at compile time.

MKing
+3  A: 
Kent Boogaart
Thanks! This pointed me in the right direction. I ended up copying the default style/template for tabs (by using Blend) and then made my style/template such that the add tab button is always next to the last tab. I can post that code if anyone is interested.
Jon Kragh
A: 

Hi,

I'm looking to do the same thing. Is it possible you could post the xaml that you used for your template?

I'm just downloading the blend trial.

Any help is much appreciated. Thanks.