Winforms: Accessibility: In Inspect: MSAA, the child items of some controls cannot be displayed, and Children property gets error

[Olina-Zhang]

• .NET Core Version:
  .Net 6.0.100-alpha.1.20516.5

• Have you experienced this same bug with .NET Framework?:
  No

• More Info

• This issue cannot repro on .Net Core 3.1.
• Affected controls: CheckedListBox, ListBox, ToolStrip, StatusStrip, ContextMenuStrip, BindingNavigator, DataGridView, ListView

Minimal repro:

1. Create a Winforms .Net Core app with controls: CheckedListBox/ListBox/ToolStrip/StatusStrip, ContextMenuStrip/BindingNavigator/DataGridView/ListView
2. Added items for these controls
3. Build and run app
4. Open the Inspect tool and observe these controls hierarchy on MSAA mode

Actual behavior:
Controls' items cannot be displayed in Inspect: MSAA

Expected behavior:
Controls' items can be displayed in Inspect: MSAA hierarchy

[merriemcgaw]

@Olina-Zhang what happens with the UIA option selected? How about Accessibility Insights for Windows? Those should be our priority now, rather than MSAA (which we used to use quite a bit).

[Olina-Zhang]

@merriemcgaw I see. Inspect:UIA, Accessibility Insights are worked well for controls hierarchy. They are our top priority. And Inspect:MSAA testing was from another issue: 4100, and @Tanya-Solyanik @dreddy-work suggest us check all controls to ensure no issue in MSAA. so filed several issues related MSAA.

[vladimir-krestov]

It can be fixed by #4168

[Marie-Shi]

Verified this issue with .Net 6.0.100-alpha.1.20562.2 from master branch, it is fixed, now controls' items can be displayed in Inspect: MSAA hierarchy.

[Zheng-Li01]

Verified this issue in .Net SDK 5.0.101 build, this issue is fixed.