Transitioner seems to hook into SelectionChanged events of descendants?

[josh2112]

Bug explanation

TL;DR: The Transitioner control is inspecting its descendants for controls that offer the SelectionChanged event and hooking their SelectionChanged events into its own. This seems like incorrect behavior; I would expect it to only report when its visible immediate child control has changed and not care about what is deep within those controls. I have a GitHub repo which demonstrates the issue in a minimum viable VS project.

I use a Transitioner to flip between several different panels, mostly programmatically. Certain panels require a little external setup when they become active, so I hook to the Transitioner's SelectionChanged event, to see which of the child panels has become active. This works great. But recently I've run into a problem: If one of those child panels have a descentant that offers its own SelectionChanged event (like ListView, TabControl, etc.), the Transitioner seems to be hooking into those events and forwarding them to its own SelectionChanged event.

GitHub repo to demonstrate: josh2112/TestTransitionerSelection

This is a VS2022 solution containing a .NET 6.0 WPF application. Just clone & run.

Click on the "next" and "prev" buttons to transition between the two panels. Watch the debug output for Transitioner.SelectionChanged being called:

10:54:13:344	Transition from FrameworkElement (name=panel1) to FrameworkElement (name=panel2)
10:54:14:089	Transition from FrameworkElement (name=panel2) to FrameworkElement (name=panel1)

Now go to panel 2 and click some list items. In the debug output you can see Transitioner.SelectionChanged is reporting those changes as well:

10:54:16:839	Transition from ListItem (text=item 3) to ListItem (text=item 4)
10:54:16:839	Transition from ListItem (text=item 4) to ListItem (text=item 3)

I can work around this issue by looking at SelectionChangedEventArgs.Source, which will report either the Transitioner or the ListView but I still feel this is strange & unexpected behavior that should be classified as a bug.

Thanks!

Version

4.9.0