How do I change the color of the Fluent Ribbon UI backstage menu which is – by default – blue?
You need to set the Backstage Background Color. This will update the MenuButton, BackstageTabItems and the swish in the corner of the backstage panel. Example below sets the color to Red.
<Fluent:Backstage Background="Red">
<Fluent:BackstageTabControl>
<Fluent:BackstageTabItem Header="New"/>
<Fluent:BackstageTabItem Header="Print"/>
</Fluent:BackstageTabControl>
</Fluent:Backstage>