In the DemoConsole application, after adding two items to the MenuStrip/ToolStrip project and clicking cancel, all items will disappear

[Nora-Zhou01]

.NET version

main branch of WinForms repo

Did it work in .NET Framework?

Not tested/verified

Did it work in any of the earlier releases of .NET Core or .NET 5+?

No

Issue description

In the DemoConsole application, after adding two items to the MenuStrip/ToolStrip project and clicking cancel, all items will disappear

cancel.issue.mp4

Steps to reproduce

Test sample: DemoConsole bases on main branch in Winforms repo.

[MelonWang1]

Verified this issue in the Winforms main branch for .NET10.0, it has been fixed. After adding two items to the MenuStrip/ToolStrip and clicking cancel, the existing items will not be affected.

10989.mp4

[Zheng-Li01]

Verified the issue with the release/10.0-preview3 branch of the latest dotnet/winforms repo, it was fixed as above testing result.