Winforms: [Accessibility] Missing the items displayed for CheckedListBox control in the inspect tool

[Zheng-Li01]

• More info

1. The issue also can reproduce on .NET 5.0 RC2.
2. The issue can't reproduce on .NET SDK 3.1 and .NET 4.8.

• .NET Core Version:
  .NET SDK 6.0.100-alpha.1.20514.15

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

Problem description:
Missing the items displayed for CheckedListBox control in the inspect tool.

Minimal repro:

1. Create a .NET Core project with a CheckedListBox control.
2. Build and run the core project.
3. Observe the checkedListBox1 control in the Inspect tool on UI Automation mode.

Expected behavior:
The items displayed correctly for checkedListBox1 control in the Inspect tool.

Actual Behavior:
Missing the items displayed for checkedListBox1 control in the inspect tool.

[Tanya-Solyanik]

@merriemcgaw - this regression makes checked list box unusable under UIA - we should consider servicing.
@Zheng-Li01 - great bug! Do you happen to know when this regressed?

[merriemcgaw]

Yes, this is something we need to service.

[Zheng-Li01]

@Tanya-Solyanik, verified the issue from 5.0.rc2 to 5.0.100-preview.1.20155.7(https://dotnet.microsoft.com/download/dotnet/5.0), the issue reproduce all the time.

[merriemcgaw]

Drat! We will get this in for 6.0 with priority and back port if needed. @vladimir-krestov - this will be on the priority list.

[RussKie]

@merriemcgaw do we want to service this in 5.0.1?

[merriemcgaw]

Yes, I agree with @Tanya-Solyanik here. We have to service or CheckedListBoxes are entirely unusable under UIA. @Pilchie for FYI.

[RussKie]

Raised https://github.com/dotnet/winforms/pull/4209 for servicing.

[Jenna-Zheng]

Verified this issue with .NET SDK 6.0.100-alpha.1.20562.2, it is fixed that the items displayed correctly for checkedListBox1 control in the Inspect tool.

[Zheng-Li01]

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