DragUI.SetContentFromSoftwareBitmap() does not show the bitmap

[wbokkers]

When setting the drag bitmap in the DragStarting event handler, the bitmap is not displayed.
To set the bitmap, I use args.DragUI.SetContentFromSoftwareBitmap(...)

Steps to reproduce the bug

1. Add an event handler to a DragStarting event
2. Create a software bitmap
3. Set the bitmap using DragUI.SetContentFromSoftwareBitmap()
4. The bitmap does not show up.

Expected behavior
The bitmap should be visible

Version Info

NuGet package version:
Microsoft.ProjectReunion 0.5.0-prerelease

Windows 10 version	Saw the problem?
May 2020 Update (19041)	Yes

[jschwizer99]

I observe the same problem with args.DragUI().SetContentFromBitmapImage(bitmap). I also do not see the image. When just calling args.DragUI() a paper sheet is shown.

[jschwizer99]

This issue could be related to #4545 as I indeed see the bitmap icon if #4545 works on a platform reliable.

[codendone]

I believe @jschwizer99 is correct that this is the same as #4545. The comment I just added to that one:

We just debugged this issue last week. This is unfortunately a bug in Windows specific to non-UWP apps. It isn't clear right now if we can fix this in WinUI3. On the plus side, this has been fixed in Windows, and is available in current Dev Channel builds from the Windows Insider Program.

In theory it is possible to avoid the issue if you can avoid any awaits (and taking a deferral) in your DragStarting handler. But that likely isn't reasonable for most uses to already have the bitmap ready.

[wbokkers]

@codendone Will the window fix also be applied to older Windows versions? WinUI Desktop is supposed to work on older Windows versions as well.

[codendone]

Backporting will be considered, but I can't guess whether it will be approved, or how far it might be backported.

[wbokkers]

ProjectReunion 0.8.0-preview regresses even more. Even the default drag UI bitmap never shows up. This was working 1 out of 5 times in Reunion 0.5.7. Overriding the bitmap still does not work.

And I still get random crashes while dragging: 0xC000027B: An application-internal exception has occurred

[codendone]

The OS fix for this issue went live on Windows Update over the last month, so fully updated machines should no longer experience this issue.

[sudongg]

The problem is easily triggered when I use StartDragAsync .
I'm confused by "This is unfortunately a bug in Windows specific to non-UWP apps" because I don't have this problem on other UI frameworks (like Google Chrome)
I would like to know if there is any workaround for this issue currently in older versions?

[stevenbrix]

@codendone this seems to still be happening on windows 11 so it seems that the OS fix from a few years ago wasn't enough?