Unable to open Split-Button flyout within a ListView using ALT + Down on the keyboard

[bbonaby]

Describe the bug

According to this old thread #1238 the correct way to open a the flyout from a split button using the keyboard is by using ALT + Down. However, when the Split-Button is in a ListView using ALT + Down moves focus from the Split-Button to the next item in the list instead of opening the Split-Button's flyout. Contrary to that information, for this scenario I'm able to open the Split-Button's menu flyout using SHIFT + ALT + Down. Can we get confirmation on whether this is intended behavior or if this is a bug?

See my test repo for a quick repro https://github.com/bbonaby/SplitButtonTestApp - Currently using WinAppSDK version 1.5.240802000

Steps to reproduce the bug

• Create a Win UI 3 app with two or more split button controls inside a ListView.
• launch the app and Tab into the ListView and then tab into the Split-Button.
• Focus will be on the entire split button, then on the Keyboard type ALT + Down arrow, you'll notice that the focus now goes to the next item in the list instead of opening the flyout.

Expected behavior

The flyout in the Split-Button opens when the Split-Button has focus and the user presses the ALT + Down keys

Screenshots

Here is a video of me using the on screen keyboard to at first attempt to open the Split-Buttons flyout with ALT + Down. Then at the end I show that I can open it with SHIFT + ALT + Down.

Repro.of.split.button.not.opening.flyout.with.alt.+.down.keys.mp4

NuGet package version

WinUI 3 - Windows App SDK 1.5.6: 1.5.240802000

Windows version

Windows 11 (22H2): Build 22621

Additional context

No response