'Object reference not set to an instance of an object.' occurs after add ToolStripMenuItem then click other area or 'type here' in DemoConsole application

[MelonWang1]

.NET version

main branch of WinForms repo

Did it work in .NET Framework?

Yes

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

No, the "type here" is not support in previous version, regress after PR 13093 merged.

Issue description

'Object reference not set to an instance of an object.' occurs after add ToolStripMenuItem then click other area or 'type here'.

null.reference.mp4

Steps to reproduce

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

More info:

1. This issue only repro in MenuStrip control in DemoConsole application.

[MelonWang1]

Verified this issue in the latest .NET 10 build: 10.0.100-preview.5.25229.109, it was fixed, now no error popup after add ToolStripMenuItem then click other area or 'type here' in DemoConsole application.

13286.mp4

[Philip-Wang01]

Verified this issue in the .NET 10 Preview 5 test pass build, it was fixed, same result as above.