Fix ToolStripMenuItem character input in design mode

[Copilot]

Fixes #13234

Proposed changes

• Add IsInDesignMode check before calling SetActiveToolStrip(this) in WM_SETFOCUS handler
• Prevents modal menu mode from intercepting keyboard input in design surfaces

PR #13034 fixed #12916 by calling SetActiveToolStrip(this) on WM_SETFOCUS, but this unconditionally enters modal menu mode which redirects keyboard input to the ToolStrip. In design mode (e.g., DemoConsole), this prevents text entry when editing menu items.

if (!IsInDesignMode)
{
    ToolStripManager.ModalMenuFilter.SetActiveToolStrip(this);
}

This follows the existing pattern at line 4614: if (!IsDropDown && !IsInDesignMode).

Customer Impact

• Users of custom design surfaces (like DemoConsole) can now enter text when adding ToolStripMenuItems
• No impact to Visual Studio designer (confirmed not to reproduce there)

Regression?

• Yes, introduced by fix #12916 Cannot use down to expand ToolStripDropDownButton in toolStrip2 after using right/Left to collapse ToolStripDropDownButton in toolStrip1 #13034

Risk

• Low: minimal change, follows existing pattern, only affects design mode behavior

Test methodology

• Code review verified pattern consistency with existing IsInDesignMode checks in same method
• Issue confirmed to not reproduce in VS designer per comment from @ricardobossan

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• st8vsblobprodcus339.vsblob.vsassets.io
  • Triggering command: /home/REDACTED/work/winforms/winforms/.dotnet/dotnet /home/REDACTED/work/winforms/winforms/.dotnet/dotnet msbuild /m /nologo /clp:Summary /v:minimal /nr:true /warnaserror /p:TreatWarningsAsErrors=true /p:ContinuousIntegrationBuild=false /home/REDACTED/work/winforms/winforms/artifacts/toolset/restore.proj /t:__WriteToolsetLocation /clp:ErrorsOnly;NoSummary /p:__ToolsetLocationOutputFile=/home/REDACTED/work/winforms/winforms/artifacts/toolset/11.0.0-beta.25571.109.txt (dns block)
  • Triggering command: /home/REDACTED/work/winforms/winforms/.dotnet/dotnet dotnet build --no-restore (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Cannot enter characters when adding ToolStripMenuItem1 and then adding ToolStripMenuItem2 after pressing enter in DemoConsole application</issue_title>
<issue_description>### .NET version

main branch of WinForms repo

Did it work in .NET Framework?

Yes

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

Yes, this is a regression issue. Not repro on .NET 9.0 from Release/9.0 branch of WinForms repo.

release9.0.mp4

Issue description

Actual result:
Cannot enter characters when adding ToolStripMenuItem1 and then adding ToolStripMenuItem2 after pressing enter in DemoConsole application.

cannot.input.mp4

Expected result:
Characters can be entered when adding ToolStripMenuItem1 and then adding ToolStripMenuItem2 after pressing enter in DemoConsole application.

framework.not.repro.mp4

Steps to reproduce

Test sample: DemoConsole bases on main branch in Winforms repo.

More info:

1. This issue rerpo in ContextMenuStrip/MenuStrip/ToolStrip/BindingNavigator control in DemoConsole application.
   </issue_description>

Comments on the Issue (you are @copilot in this section)

@merriemcgaw @LeafShi1 can your team look into this one? @ricardobossan The issue is caused by commit #13034: `fix #12916 Cannot use down to expand ToolStripDropDownButton in toolStrip2 after using right/Left to collapse ToolStripDropDownButton in toolStrip1`.

Still need to find a solution that resolves both this regression and the original problem from #12916 without reintroducing either.

git bisect log

git bisect start
status: waiting for both good and bad commits
good: [78c7bb8] System.Data.SqlClient - use version recommended by the SQL team, I couldn't find v5, not sure if it exists, we are not referencing this package right ow, so this is not a problem. Nuget.Packaging - use version that does not pull in vulnerable System.Formats.Asn1 (v8.0,0) Change in the VB test project - this assembly is not references directly, transitive versions can be resolved from the central packaging
git bisect good 78c7bb8
status: waiting for bad commit, 1 good commit known
bad: [9092b06] [main] Update dependencies from dotnet/runtime (#13363)
git bisect bad 9092b06
bad: [1a43082] Ensure that System.Drawing facade assembly is built before the tests that consume it are. (#13119)
git bisect bad 1a43082
bad: [1a43082] Ensure that System.Drawing facade assembly is built before the tests that consume it are. (#13119)
git bisect bad 1a43082
good: [707898d] [main] Update dependencies from dotnet/arcade (#13032)
git bisect good 707898d
bad: [316a77b] Remove extra dot at the end of resource string (#13091)
git bisect bad 316a77b
bad: [5e8147d] Resizes DemoConsole project's MainForm for convenience and to make everything visible in the surface designer (#13050)
git bisect bad 5e8147d
bad: [6e112b8] fix #12916 Cannot use down to expand ToolStripDropDownButton in toolStrip2 after using right/Left to collapse ToolStripDropDownButton in toolStrip1 (#13034)
git bisect bad 6e112b8
good: [e9f1c43] Enable nullability in DesignerActionMethodItem (#12676)
git bisect good e9f1c43
good: [e65c611] [main] Update dependencies from dotnet/arcade (#13038)
git bisect good e65c611
good: [2dc1fbe] Add code coverage for ControlCodeDomSerializer (#13011)
git bisect good 2dc1fbe
first bad commit: [6e112b8] fix #12916 Cannot use down to expand ToolStripDropDownButton in toolStrip2 after using right/Left to collapse ToolStripDropDownButton in toolStrip1 (#13034)

@ricardobossan<...

• Fixes Cannot enter characters when adding ToolStripMenuItem1 and then adding ToolStripMenuItem2 after pressing enter in DemoConsole application #13400

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.15474%. Comparing base (09c759b) to head (4714510).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #14078         +/-   ##
===================================================
- Coverage   77.16719%   77.15474%   -0.01246%     
===================================================
  Files           3279        3279                 
  Lines         645317      645320          +3     
  Branches       47718       47719          +1     
===================================================
- Hits          497973      497895         -78     
- Misses        143657      143729         +72     
- Partials        3687        3696          +9     

Flag	Coverage Δ
Debug	77.15474% <100.00000%> (-0.01246%)	⬇️
integration	18.98213% <100.00000%> (-0.03711%)	⬇️
production	52.01845% <100.00000%> (-0.02764%)	⬇️
test	97.40749% <ø> (ø)
unit	49.47212% <100.00000%> (-0.00053%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.