ToolStripDropDown top scroll button cannot scroll to the visible item before a hidden item

[Olina-Zhang]

.NET version

.NET 11 SDK build: 11.0.100-preview.5.26256.117

Did it work in .NET Framework?

No

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

No, repro in previous .NET versions

Issue description

ToolStripDropDown scrolling behavior issue when hidden items exist in the dropdown.
Given four dropdown items:

• A
• B
• C
• D

with: B.Visible = false;

At runtime, the dropdown can scroll downward correctly, but upward scrolling using the top scroll button stops at C and cannot continue scrolling back to A, which is the visible item immediately before the hidden item B.

ScrollingIssue.mp4

Steps to reproduce

1. Create a ToolStripDropDownButton (or similar dropdown control).
2. Add four dropdown items:

• A
• B
• C
• D

3. Set: B.Visible = false;
4. Configure the dropdown height so scrolling buttons appear.
5. Run the application.
6. Scroll downward until lower items are visible.
7. Use the top scroll button to scroll upward.