Hi Tommy,
Any time a Ribbon is loaded up, it tries to find an ancestor RibbonWindow. If it finds one, it registers itself with that RibbonWindow. Only one Ribbon can be registered with a RibbonWindow at a time. So what happened in that other thread was that the order of the Ribbons was flipped in the XAML. Meaning that say the Ribbons were defined in the same ancestor Grid. The order that the Ribbons appeared in the XAML were flipped even though they kept the same Grid display locations. That way, the more important Ribbon was associated with the RibbonWindow instead of the other way around. Please try that and see if it helps.