[Windows] Fix TitleBar color not applied to the Flyout icon background during initial loading

[Tamilarasan-Paranthaman]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Root Cause of the Issue:

• The NavigationViewControl ButtonHolderGrid color was not properly updated at initial loading. At initial loading the ButtonHolderGrid is null due to this the color was not updated properly.

Description of Change

• The color is now updated after ApplyTemplate has completed. This ensures that ButtonHolderGrid is no longer null, and the color is now applied correctly during initialization.

Screenshot

Before Fix	After Fix
Before-Fix.mp4	After-Fix.mp4

Issues Fixed

Fixes #25081

[sheiksyedm]

/azp run MAUI-UITests-public

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull request overview

This PR fixes a Windows-specific issue where the TitleBar background color was not properly applied to the Flyout icon background during initial loading. The root cause was that ButtonHolderGrid was null during initial template setup. The fix ensures UpdateBackgroundColorForButtons() is called after ApplyTemplate completes, when ButtonHolderGrid is guaranteed to be available.

Key Changes

• Adds a call to UpdateBackgroundColorForButtons() after template application completes in WindowRootView.cs
• Includes UI tests to verify both initial color application and dynamic color changes
• Tests run on Windows and MacCatalyst platforms where TitleBar is supported

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/Core/src/Platform/Windows/WindowRootView.cs	Adds call to UpdateBackgroundColorForButtons() in OnNavigationViewControlOnApplyTemplateFinished to ensure color is applied after template is ready
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25081.cs	Adds NUnit UI tests to verify initial and dynamic flyout icon background color application
src/Controls/tests/TestCases.HostApp/Issues/Issue25081.cs	Adds Shell-based test page with TitleBar and button to test color changes

[Copilot]

Test methods should return void instead of async Task when they don't contain any await statements. The async keyword is unnecessary here since no asynchronous operations are being performed.

Change to:

public void VerifyFlyoutIconBackgroundColor()

[Copilot]

Test methods should return void instead of async Task when they don't contain any await statements. The async keyword is unnecessary here since no asynchronous operations are being performed.

Change to:

public void VerifyDynamicFlyoutIconBackgroundColor()

Suggested change

	public async Task VerifyDynamicFlyoutIconBackgroundColor()
	public void VerifyDynamicFlyoutIconBackgroundColor()