WebView2 on Custom Desktop without Explorer.exe

[dbuechel]

We plan to integrate WebView2 into our lockdown application Safe Exam Browser. We're using CreateDesktop and its related functions to create and activate a custom desktop on which we run our main UI. In the process of implementing the WebView2 integration, we had to notice that it doesn't seem to work on our custom desktop where explorer.exe isn't running.

We have found quite an old issue on the topic (#48), but are not sure whether it still is accurate. Thus we'd first like to ask whether you could confirm that the incompatibility is still the case, and secondly, if it is, whether there are any plans to make WebView2 work on custom desktops?

AB#31945291

[dbuechel]

@champnic @jasonstephen15 We were planing to integrate WebView2 in our next version, but are currently blocked due to this problem. Would it be possible for someone from MSFT to have a look at this issue and potentially provide feedback?

[champnic]

@dbuechel Sorry this is causing problems and blocking you. I don't think anyone has tested desktop compatibility since that issue you linked, and we don't have current plans in this area. Are you running into a particular bug or exception when trying to launch WebView2 on the custom desktop? If so can you add info and describe your repro steps in detail or provide a sample app?

[dbuechel]

Thanks a lot for your response. I haven't noticed any exception or alike, the problem is that the WebView2 content area remains empty (white), a few times the content was rendered but then disappeared once interacting with it. There also were severe rendering issues (black squares) when resizing the window holding the WebView2 control.

You can test the behavior by installing the following development build of Safe Exam Browser (the setup bundle automatically installs the correct version and dependencies, though not yet the WebView2 runtime which you'd have to install manually): https://sebdev-let.ethz.ch/project/AppVeyor/seb-win-refactoring/builds/299/job/dxao0jjj8plp1rp6/artifacts

[champnic]

Thanks for the repo app - I've added this as a bug on our backlog.

[dbuechel]

Excellent, thanks a lot! We would really like to eventually also replace our main browser engine (CefSharp / CEF) with WebView2, but as long as this incompatibility exists, we won't be able to do so.

[dbuechel]

@champnic Is there any chance that you could specify a time horizon for this issue? We happen to be blocked by several issues in our current browser engine and would thus like to replace it with WebView2 as soon as possible (i.e. once this issue is fixed).

[champnic]

No specific timeline yet, but I've just upped the priority on it. We'll try to start taking a look next week.

[dbuechel]

Great, good to know and thanks a lot for the excellent support!

[bhiggins107]

Is this issue going to get fixed this time? It has been raised previously for both WebView and WebView2 with no resolution.

We are effectively seeing the same issue, where WebView2 fails to initialize if explorer.exe is not running.

Exception:
Type: System.Runtime.InteropServices.COMException
Message: Element not found. (Exception from HRESULT: 0x80070490)
Source: mscorlib
Stacktrace: at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo)
at System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(Int32 errorCode)
at Microsoft.Web.WebView2.Core.CoreWebView2Environment.d__32.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.Web.WebView2.Wpf.WebView2.<>c__DisplayClass25_0.<g__Init|0>d.MoveNext()