[Accessibility] ToolStrip (TabStop=true) intercepts arrow keys after tab navigation, preventing TreeView from handling them (.NET 10 regression)

[Olina-Zhang]

.NET version

.NET 11 SDK build: 11.0.100-preview.4.26211.102

Did it work in .NET Framework?

Yes

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

Yes, It's a regression issue in .NET10/.NET11, cannot repro in .NET 9.0/8.0

Issue description

When a TreeView is followed by a ToolStrip/ MenuStrip / StatusStrip with TabStop = true. After cycling focus using Tab, TreeView no longer receives arrow key input (e.g., Right Arrow), and the key is instead used for focus navigation.

The issue is not limited to TreeView. It also reproduces with ListView and DataGridView, and affects all arrow keys (Left, Right, Up, Down).

First interaction

• Press Tab to focus TreeView
• Press → (Right Arrow) → node expands
• Press ← (Left Arrow) → node collapses

Second interaction

• Press Tab to move focus to ToolStrip
• Press Shift+Tab to return focus to TreeView
• Press → (Right Arrow)

Result: The selected TreeNode does not expand and TreeView does not handle the key, but focus moves to ToolStrip instead

ToolStripIssue.mp4

Steps to reproduce

1. Create a WinForms .NET 10/11 app
2. Add controls in this order:

• Button
• TreeView (with leaf nodes)
• ToolStrip with one item, set:
  toolStrip1.TabStop = true;

3. Run the app:

First interaction

4. Press Tab to focus TreeView
5. Press → (Right Arrow) → node expands
6. Press ← (Left Arrow) → node collapses

Second interaction

7. Press Tab to move focus to ToolStrip
8. Press Shift+Tab to return focus to TreeView
9. Press → (Right Arrow)

[SimonZhao888]

This issue was introduced by PR #13034