[Windows] Fix for Assigning null to the SelectedItem of the CollectionView in the SelectionChanged event does not clear the selection

[SyedAbdulAzeemSF4852]

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!

Issue Details

• Setting SelectedItem to null in the SelectionChanged event does not clear the selection in the collection view.

Root Cause

• In the UpdateVirtualSingleSelection method, the VirtualSelectionChanged event handler is temporarily unsubscribed to avoid recursive updates when setting ItemsView's SelectedItem. However, because the selection is updated while the event is unwired, the SelectionChanged event does not fire. As a result, the VirtualSelectionChanged method is never called, and UpdatePlatformSelection method is not invoked. This results in the selection not being cleared.

Description of Change

• Added a new _ignoreVirtualSelectionChange flag to SelectableItemsViewHandler to prevent unnecessary updates during virtual selection changes.

Issues Fixed

Fixes #10025

Validated the behaviour in the following platforms

• Windows
• Android
• iOS
• Mac

Output

Before	After
Before.mp4	After.mp4

[dotnet-policy-service]

Hey there @@SyedAbdulAzeemSF4852! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.