Add SegmentedItemBackgroundBrushTransition resource

[AndrewKeepCoding]

Fixes #305

Adds a resource to override the BackgroundTransition to avoid conflicts with the VisualState changes when SegmentedItem doesn't use the default Background.

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

What is the new behavior?

PR Checklist

Please check if your PR fulfills the following requirements:

• Created a feature/dev branch in your fork (vs. submitting directly from a commit on main)
• Based off latest main branch of toolkit
• Tested code with current supported SDKs
• New component
  • Documentation has been added
  • Sample in sample app has been added
  • Analyzers are passing for documentation and samples
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• Tests for the changes have been added (if applicable)
• Header has been added to all new source files
• Contains NO breaking changes

Other information

[niels9001]

Great catch! Do you have a small screencapture of the new effect?

[AndrewKeepCoding]

Great catch! Do you have a small screencapture of the new effect?

<Page.Resources>
    <win:BrushTransition x:Key="SegmentedItemBackgroundBrushTransition" Duration="0:0:0.000" />
</Page.Resources>

Recording.2026-01-06.222436.mp4