Hi Jonas Hero,
I am sorry for the delayed reply.
I have three suggestions:
In versions prior to Q1 2010:
The TabControl supports orientation and we apply a transformation to one of its template parts. Quite possibly we override your transformation in code.
If you apply the transformation on a wrapper element (or anywhere else actually), it should work.
2. The TabItem has four templates - Top / Left / Right / Bottom - one for each position of the TabStripPlacement of the TabControl.
When you create a custom template, it should be assigned to the orientation-specific template or it may get overriden.
In versions after Q1 2010:
3. All transformations to elements in the control template are applied with VisualStates and just one template is used (the control.Template). IMO the new template will be easier to edit.
Does this work for you?
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