ListBox inside Popup not scrolling with PointWheelChanged

[gebodal]

Describe the bug

On Windows, the pointer scrollwheel is not scrolling a ListBox inside a Popup (no error thrown, but no effect on the control). The ListBox responds to the scrollwheel as expected when inside a Grid (or StackPanel).

However, on Ubuntu and Mac, the ListBox responds as expected in both situations.

To Reproduce

This project contains an example of the issue: ListBoxScrollTest.zip

Tested with the desktop lifetime, on Windows 10 Home and Ubuntu 20.04 (and MacOS, but I'm afraid I borrowed that, and I didn't note down the OS version).

Expected behavior

The PointerWheelChanged event should cause the ListBox to scroll regardless of whether it is a child of a Grid or a Popup.

Avalonia version

11.1.2

OS

Windows

Additional context

The PointerWheelChanged event does not propagate to the ListBox control when inside the Popup, and only gets as far as the LightDismissOverlayLayer, as seen in DevTools when the mouse wheel is scrolled over the control (Windows 10 Home):

So the scrollwheel has no effect on that ListBox.

For the ListBox that is a direct child of the Grid, the event propagates fully into the ListBox template elements (Windows 10 Home):

[gebodal]

(Apologies for the close/unclose, clicking all the wrong buttons today)

[stevemonaco]

Need some clarity here. I ran the repro on Win11 and get the following behaviors:

1. The ListBox-in-Grid scrolls with mouse wheel when hovered.
2. The ListBox-in-Popup scrolls with mouse wheel when hovered.
3. The ListBox-in-Popup and ListBox-in-Grid do not scroll with mouse wheel when the cursor is outside of the Popup bounds.

Which scenario is at issue or is it something else? A short screen capture might help here.

[gebodal]

It’s scenario 2 that isn’t working on my machine. None of the following cause scrolling for scenario 2:

• a. Click button, move cursor over ListBox, scroll.
• b. Click button, move cursor over ListBox, click on ListItem (so that it’s highlighted), keep cursor over ListBox, scroll.
• c. Click button, use cursor to click-drag ListBox ScrollBar, scroll.

I can try and get a screen capture for you, but it would mostly be things not happening, so I’m not sure how helpful that would be. Would it be useful to have DevTools output as well? What would be the information to show? (Apologies, I’m new to debugging Avalonia like this)

[gebodal]

Something like this?

https://github.com/user-attachments/assets/0db1cb2a-3023-4fed-bdf2-839696b7c2d6

[stevemonaco]

Weird. I only get (Win11) the tunnel event through LightDismissOverlayLayer while not hovering the ListBox-in-Popup. When hovering, it properly goes through the ContentPresenter, MainView, etc.

[gebodal]

I'm not getting LightDismissOverlayLayer when hovering outside of both ListBoxes? It just tunnels MainWindow > Panel > Panel and then bubbles back out again.

[gebodal]

As in:

https://github.com/user-attachments/assets/ddc4a8ac-22ca-419d-8c52-1a1897ca8ef6