The ToolStripScrollDownButton should be disabled when displaying and focused on the last dropdown item in order to avoid an exception popping up

[Olina-Zhang]

• .NET Core Version: 7.0.100-preview.2.22103.2

• Have you experienced this same bug with .NET Framework?: Yes

Repro steps:

1. Create a Winforms .Net Core application
2. Add a toolStrip on the form designer
3. Add a toolStripDropDownButton on the toolStrip
4. Add several drop down items under toolStripDropDownButton
5. In the Form.Designer.cs file, edit height of the this.toolStripDropDownButton1.DropDown.MaximumSize property in order to just display one or a part of one drop down item

Or using attached app: WinFormsApp91.zip

6. Build and run app, then click ToolStripScrollDownButton to display the last dropdown item

Actual behavior: The ToolStripScrollDownButton is still enabled when displaying the last dropdown item, and in this case, an exception pops up when clicking that ToolStripScrollDownButton again

Expected behavior: When go through the last dropdown item, the ToolStripScrollDownButton is disabled

[ghost]

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