In-app toolbar (XAML Visual Tree) can't select Popup elements

[whiskhub]

Describe the bug

The black in-app toolbar at the top of a debugged WinUI 3 window has a feature to select an element in the XAML visual tree by clicking on it.
Unfortunately, elements within popups cannot be selected using this method. Only elements behind the popup are selected.

Steps to reproduce the bug

1. Add any kind of popup to your WinUI 3 app (preferably something that stays open, e.g. ContentDialog)
2. Open the popup
3. Click in the in-app toolbar on the "Select element Ctrl+Shift+K, C" button
4. Try to select any element within the popup

Expected behavior

I can select elements within popups/ContentDialogs using the in-app toolbar, to debug them in the XAML visual tree.

Screenshots

The element behind the popup is selected instead of the one in the ContentDialog.

NuGet package version

WinUI 3 - Windows App SDK 1.5.5: 1.5.240627000

Windows version

Windows 11 (22H2): Build 22621

Additional context

Note: this is a regression from WinUI 2 and WPF, where this works without a problem.

Sometimes with WPF I've seen additional in-app toolbars appear for additional (popup) windows. Maybe this would at least be a temporary improvement compared to the current WinUI 3 behavior.