Moving mouse wheel and click hangs WinUI application

[wesol1]

MoveMouseWheelAndClick.mp4

Describe the bug

It's introduced from the first version of 1.4 (with last 1.3 works well).
When you move mouse wheel and quick/accidentally click left/right mouse button application hangs.
Moving pointer cursors outside the app or switching to another one brings it back to life.
You can observe such thing with WinUI 3 Gallery app.

Steps to reproduce the bug

1. Open WinUI app (or WinUI 3 gallery)
2. Start moving the mouse wheel and then quick click left/right mouse button
3. Try couple of times if not successful

Expected behavior

Application should be responsive not frozen.

Screenshots

Movie added as attachment.

NuGet package version

Windows App SDK 1.4.3: 1.4.231115000

Packaging type

No response

Windows version

No response

IDE

Visual Studio 2022

Additional context

In attached movie I used WinUI 3 Gallery app, as I cannot show you our commercial one.
Such freeze was introduce with first 1.4 version, probably with new Scrollxxx features.

[kmgallahan]

@bpulliam Confirmed, although not for all controls. If any bug were to be high-priority this would be one, yes?

[wesol1]

One more thing, I was able to freeze Windows Explorer in Home and Gallery folders, same way. :-(

[jeremy-visionaid]

I just hit this one too when trying to implement to some custom gesture recognizers, though I don't think "hang" is quite an accurate description. The dispatcher is still processing events, but no pointer events are being raised for them to have any effect. It's most easily reproducible for me by scrolling the mouse wheel while simultaneously clicking it.

I observe the following sequence of events, after which no further events are raised until the cursor is moved outside the affected window:

1. PointerPressed
2. PointerCanceled
3. PointerReleased

[jeremy-visionaid]

FWIW, I have a repro here to show that pointer events are no raised after clicking while the mouse wheel is being scrolled:
https://github.com/molesmoke/WinUITestApp/tree/pointer-event-loss

I tried to work around the issue by moving the cursor outside the window briefly via API calls when the event loss is detected, but to no avail.

[mikolaj-boc]

Spotted the same issue in our app here! Please prioritize if possible, thanks.
Repro steps:

• use the WinUI 3 gallery app
• Press middle mouse button and start scrolling up and down (anywhere)
• Sometimes this will trigger a PointerCanceled event. The pointer associated with the mouse will now become defunct. The only way to 'heal' it is to move the mouse pointer outside of the app and back again.

[mikolaj-boc]

scrollissue.mp4

Some desc: I'm pressing MMB and scrolling simultaneously. Then we can observe that the mouse pointer stops working - there's no visual feedback from the elements in the app. I move the pointer outside of the app and back again - the pointer works again.

[jeremy-visionaid]

Still present in v1.4.231219000

[KenionX]

I can reproduce it also in my windows explorer, what a nice bug :D

[jeremy-visionaid]

I think this was the wrong repo to file the issue against (since it seems to be a WinUI 3 bug, not a Win App SDK model issue), so I've opened it on https://github.com/microsoft/microsoft-ui-xaml and linked that to here so it can hopefully get the attention of the right people.

[mikolaj-boc]

Hi @llongley, thanks for the fix! Do you happen to know when a build with the fix is expected?

[TheEdster3]

Would also love to know when the fix would be available. A few weeks off from a release and trying to determine if we need to put the effort into some kind of workaround or not. :)

[codendone]

Status update: The fix is currently in for the upcoming 1.5 release and will be evaluated later this week for potential servicing to 1.4.

[jeremy-visionaid]

Doesn't look like the release notes have been updated yet, but I'm no longer able to reproduce it on 1.4.24021100

https://learn.microsoft.com/en-us/windows/apps/windows-app-sdk/stable-channel

[codendone]

@jeremy-visionaid Yes, the fix is part of the 1.4.24021100 release. Thanks for confirming it is working for you!