[VisualStylesMode: Net11] An exception pops up for checkbox after setting the FlatStyle = System & Appearance = ToggleSwitch with set VisualStylesMode as NET11

[Zheng-Li01]

.NET version

11.0.0-preview.7.26365.114 + private dlls built from Net11/Integration-2 branch of https://github.com/KlausLoeffelmann/winforms repo

Did it work in .NET Framework?

Not tested/verified

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

This is new API introduced by #14746

Issue description

An exception pops up for checkbox after setting the FlatStyle = System & Appearance = ToggleSwitch with set VisualStylesMode as NET11

Steps to reproduce

1. Create a .NET winforms project
2. Set the VisualStylesMode as NET11 for the form1
3. Add CheckBox contorl on the form1.cs[Design]
4. Set the Appearance as  ToggleSwitch & FlatStyle as System for the checbox1
5. Build & run the project
6. Click the checkbox1

**Call Stack: **

See the end of this message for details on invoking 
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Windows.Forms.CheckBox.get_DownChangeRectangle() in C:\Klaus\winforms\src\System.Windows.Forms\System\Windows\Forms\Controls\Buttons\CheckBox.cs:line 420
   at System.Windows.Forms.ButtonBase.OnMouseDown(MouseEventArgs mevent) in C:\Klaus\winforms\src\System.Windows.Forms\System\Windows\Forms\Controls\Buttons\ButtonBase.cs:line 965
   at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks) in C:\Klaus\winforms\src\System.Windows.Forms\System\Windows\Forms\Control.cs:line 11756
   at System.Windows.Forms.Control.WndProc(Message& m) in C:\Klaus\winforms\src\System.Windows.Forms\System\Windows\Forms\Control.cs:line 12700
   at System.Windows.Forms.ButtonBase.WndProc(Message& m) in C:\Klaus\winforms\src\System.Windows.Forms\System\Windows\Forms\Controls\Buttons\ButtonBase.cs:line 1516
   at System.Windows.Forms.NativeWindow.Callback(HWND hWnd, UInt32 msg, WPARAM wparam, LPARAM lparam) in C:\Klaus\winforms\src\System.Windows.Forms\System\Windows\Forms\NativeWindow.cs:line 351


************** Loaded Assemblies **************

[Zheng-Li01]

Tested the fix in .NET 11/Integration-3: #14768, it was fixed: