Pressing TAB key on last focusable element crashes WebView2 inside Excel VSTO Task Pane

[blair-halenda]

Description
Tabbing through elements in WebView2 (inside a VSTO task pane) works until the last web page element. Upon pressing TAB key again, the task pane freezes and Excel becomes unresponsive. This also occurs when pressing SHIFT + TAB on first web page element.

Initializing a Windows Form outside of the task pane (in the same application) performs as expected (with the last TAB returning to the top of the web page), so this must be an issue with parent COM objects.

My code already incorporates the proposed solutions from both #404 & #405.

No call-stack available. Excel freezes and Visual Studio debugger says "The application is in break mode". While debugging I was able to (by fluke) step into the WebView2 code and found a NullReferenceException, but I'm unable to reproduce.

Version
SDK: 1.0.674-prerelease
Runtime: Evergreen Distribution 86.0.622.58
Framework: Net Framework: 4.7.2, VSTO, WinForms (inside COM object)
OS: Win10

Repro Steps
Place WebView2 inside VSTO task pane. Press TAB on last element (or SHIFT + TAB on first element).

Expected: Web page focus returns to first focusable element in web page.
Actual: Application freezes/becomes unresponsive.

Excited about using WebView2 inside our VSTO addin and appreciate the hard work!

AB#30555786

[blair-halenda]

Hi, wondering if there's any update on this issue? Is there any other information you require? Thanks!

[champnic]

Sorry I missed this one - I've now added it to our backlog. I don't have a timeline on when we can investigate further - as a potential fix, can you try putting the WebView2 inside of another focusable control within the task pane? Thanks!

[blair-halenda]

Thanks for the suggestion. I've tried nesting in different focusable controls and have done extensive experimenting with different settings to no avail. This is concerning because it crashes our software and there's no way for us to develop a workaround. We're looking to launch within the next few weeks. Is there any way that I could contribute to a fix?

[champnic]

Do you have a minimal sample app that reproduces the issue that I could try out?

[blair-halenda]

I managed to get the exception to appear again, see below for the repo and exception screen capture. Feel free to reach out if you have any questions.
https://github.com/blair-halenda/WebView2Addin

[champnic]

Thanks for the sample app! Was able to repro and know what the issue is - our WebView2 Winforms control is assuming it's on a Form and using FindForm() when trying to move focus to the next control. This should be relatively easy to fix on our end, but in the meantime I haven't been able to find a workaround.

[blair-halenda]

Thank you for looking into this, that's great to hear! Do you have a time estimate for when I can expect a fix?

[champnic]

Assuming we follow our regularly scheduled process, the fix will be in the next prerelease package, sometime in January.

[ShaunLoganOracle]

I still see the same (or a very similar) issue using WebView2 (Winforms) in an Excel VSTO Task Pane using SDK 1.0.705.50, RT Evergreen 88.0.705.68

[blair-halenda]

@champnic do you have an updated ETA on this? There's been two new prereleases since this issue was posted and it still hasn't been resolved. Is there anything else I can do to help? Even a try catch on the control before calling .SelectNextControl() to prevent the crash would help significantly.

[champnic]

@blair-halenda Sorry about the delay - we had some priority reshuffling. We are actively looking at this issue this sprint.

[johna-ms]

@blair-halenda I'm investigating this and just wanted to update. This seemed like a straightforward fix at first, but I'm finding that I'm now running into a new issue where the crash no longer repros and I'm getting an infinite hang instead. This is called out in #933 which I'm also investigating. Sorry for the hold up!

[blair-halenda]

Hi @johna-ms, I appreciate the update. The infinite hang is the error, and it's reproduceable (just checked with 1.0.824-prerelease). Before debugging, I had to uncheck Just My Code to see the exception. I've added a new section to my repo to show you how to set up your environment. Let me know if you're able to see the exception.

https://github.com/blair-halenda/WebView2Addin/blob/master/README.md#setting-up-debug-environment

[johna-ms]

Ahhh I see. Unchecking Just My Code let's me see the exception. How odd for that to manifest as an infinite hang.. Thanks though!

[champnic]

This should be fixed in the latest prerelease SDK, 1.0.865-prerelease. Thanks!