How can I set the font size for the

So

took a copy of DockingWindow.xaml

was going to modify the  contenst DockingWindowTabbedMdiDocumentTemplateKey

but just merding my owne copy of "DockingWindow.xaml" (without any changes) to the resourcedicionary

caused the TabHeader background to dissapear.

I am wondering if I need to remerge something else after that or some other sequencing thing.

Thanks

JES

Hello,

I am assuming you are trying to merge this into your App.Resources?  You might need to take out the x:Key attributes for the "default styles" where the x:Key is the target control type and just leave TargetType in.  That way they become implicit styles.