ComboBox dropdown button disappear when switching RightToLeft property

[Liv-Goh]

.NET version

.NET 10 and .NET9 both having this issue

Did it work in .NET Framework?

Yes

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

This issue cannot reproduce in .NET 8, so this is a regression issue.

Issue description

Current Behavior (.NET 9.0 and 10.0)

When change the RightToLeft property after expanding the Popup FlatStyle comboBox, the dropdown button on the comboBox disappeared
When hover cursor to the disappeared dropdown button, the dropdown button will appear again.

Expected Behavior (.NET 8.0)

When change the RightToLeft property after expanding the comboBox, dropdown button on the comboBox won't be affected.

Steps to reproduce

1. Open the test app
2. Build and run the project
3. Click the dropdown button to expand the comboBox (this step is compulsory)
4. Change the comboBox RightToLeft property
5. Observe the dropdown button on the comboBox

Test app: ComboBox Dropdown issue.zip

[LeafShi1]

This issue caused by PR #11529

[Tanya-Solyanik]

Let's undo #11529 and re-activate the bug and try to fix it again

[MelonWang1]

Verified the issue with latest .NET SDK 10.0.100-alpha.1.25065.19 build, the issue has been fixed as below screenshot：

12590.mp4

[Nora-Zhou01]

Verified the issue with 9.0.0 + private dlls built from release/9.0 branch, the issue has been fixed same as above test results.

[Liv-Goh]

Verified with .NET SDK 10.0 P1 test pass build, it was fixed as above testing result.

[Philip-Wang01]

Verified with .NET SDK 9.0.3 test pass build, the issue has been fixed same as above test results.