Fix 13077 Add missed events to ToolStripDesigner

[LeafShi1]

Fixes #13077

Proposed changes

• Update the ToolStripDesigner following by VS repo

Customer Impact

• The "Type Here" item can be show in MenuStrip control and ToolStrip control in DemoConsole application

Regression?

• No

Risk

• Minimal

Screenshots

Before

After

Test methodology

• Manually

Test environment(s)

• .net 10.0.0-preview.3.25154.11

Microsoft Reviewers: Open in CodeFlow

PR Overview

This pull request updates the ToolStripDesigner to add missing event-handling and improve event subscription and disposal logic, addressing issue #13077.

• Added missing UndoEngine field and its event subscriptions.
• Updated and refactored event hook-ups and unsubscriptions for the overflow drop-down and related components.
• Cleaned up array initializations and simplified property implementations.

Reviewed Changes

File	Description
src/System.Windows.Forms.Design/src/System/Windows/Forms/Design/ToolStripDesigner.cs	Updates to event subscription, disposal routines, and minor code cleanups to match the VS repository changes

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

src/System.Windows.Forms.Design/src/System/Windows/Forms/Design/ToolStripDesigner.cs:996

• [nitpick] Consider clarifying this comment to explain what 'DummyItem' refers to, for improved readability.

// We are DummyItem to the ToolStrip.

[codecov]

Codecov Report

Attention: Patch coverage is 57.60870% with 39 lines in your changes missing coverage. Please review.

Project coverage is 61.33731%. Comparing base (eaaf38c) to head (d4f90c1).
Report is 29 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #13093         +/-   ##
===================================================
+ Coverage   61.28341%   61.33731%   +0.05389%     
===================================================
  Files           1541        1543          +2     
  Lines         158281      158393        +112     
  Branches       14743       14754         +11     
===================================================
+ Hits           97000       97154        +154     
+ Misses         60584       60543         -41     
+ Partials         697         696          -1     

Flag	Coverage Δ
Debug	61.33731% <57.60870%> (+0.05389%)	⬆️
integration	10.73083% <0.00000%> (-0.00690%)	⬇️
production	39.22659% <57.60870%> (+0.07643%)	⬆️
test	95.67698% <ø> (+0.00418%)	⬆️
unit	36.64961% <57.60870%> (+0.07677%)	⬆️

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[Epica3055]

        _undoEngine?? = GetService(typeof(UndoEngine)) as UndoEngine;

        if (_undoEngine is not null)
        {
            _undoEngine.Undoing += OnUndoing;
            _undoEngine.Undone += OnUndone;
        }