KeyboardToolTipStateMachine KeyNotFoundException thrown

[campbell-powerbrick]

.NET version

.NET 10.0.9

Did it work in .NET Framework?

Yes

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

Tested in .NET 5 and it also threw the same exception

Issue description

Since migrating a .NET Framework WinForms solution to .NET 10 I've been getting KeyNotFoundException's occurring/being thrown - seemingly by Framework code. I've added a minimal reproducible example

System.Collections.Generic.KeyNotFoundException
  Message=The given key was not present in the dictionary.
  StackTrace:
   at System.Windows.Forms.KeyboardToolTipStateMachine.Transition(IKeyboardToolTip tool, ToolTip tooltip, SmEvent event)
   at System.Windows.Forms.KeyboardToolTipStateMachine.Transit(SmEvent event, IKeyboardToolTip source)
   at System.Windows.Forms.NativeWindow.Callback(HWND hWnd, UInt32 msg, WPARAM wparam, LPARAM lparam)
   at Windows.Win32.PInvoke.DispatchMessage(MSG* lpMsg)
   at System.Windows.Forms.Application.LightThreadContext.FPushMessageLoop(msoloop uReason)
   at System.Windows.Forms.Application.LightThreadContext.RunMessageLoop(msoloop reason, Boolean fullModal)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(msoloop reason, ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at Program.Main() in ...\Program.cs:line 12

Steps to reproduce

using System;
using System.Drawing;
using System.Windows.Forms;

internal static class Program
{
    [STAThread]
    private static void Main()
    {
        Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
        Application.ThreadException += (_, e) => MessageBox.Show(e.Exception.ToString(), "Reproduced");
        Application.Run(new ReproForm());
    }
}

internal sealed class ReproForm : Form
{
    private readonly TextBox _first = new TextBox() { Text = "First", Left = 20, Top = 30, Width = 200, TabIndex = 0 };
    private readonly TextBox _second = new TextBox() { Text = "Second", Left = 250, Top = 30, Width = 200, TabIndex = 1 };
    private readonly ToolTip _toolTip = new ToolTip()
    {
        InitialDelay = 50,
        ReshowDelay = 25,
        AutoPopDelay = 100,
        ShowAlways = true
    };
    private bool _redirected;

    public ReproForm()
    {
        Text = "Hold Tab for one second";
        ClientSize = new Size(470, 90);
        Controls.AddRange(new[] { _first, _second });
        _toolTip.SetToolTip(_first, "First tooltip");
        _toolTip.SetToolTip(_second, "Second tooltip");
        _toolTip.Popup += (_, __) =>
        {
            if (_redirected || !_second.Focused)
                return;

            _redirected = true;
            _first.Focus();
        };

        Shown += (_, __) => _first.Focus();
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
            _toolTip.Dispose();

        base.Dispose(disposing);
    }
}

[Olina-Zhang]

Also reproduce this issue in .NET framework 4.8.1 app when enabling tooltip quirk in application's app.config file:

<runtime>
	<AppContextSwitchOverrides value="Switch.System.Windows.Forms.UseLegacyToolTipDisplay=false" />
</runtime>

[KlausLoeffelmann]

@LeafShi1, this is a migration blocker from earlier NetFx version, FWIW.
I think this is more than Prio 2.

[Zheng-Li01]

Verified the issue with .NET 11.0.100-preview7.26365.114 build, the issue has been fixed that no exception pops as below screenshot.

VerifyIssue.mp4

[Amy-Li03]

Verified on .NET 11 Preview 7 test pass build: .NET 11.0.100-preview.7.26381.103, issue was fixed, test result is same as above.