WinForms - Add support for OOP Designer (VS2022)

[amaitland]

The new OOP designer likely requires a new design time class.

Details in https://devblogs.microsoft.com/dotnet/state-of-the-windows-forms-designer-for-net-applications/

https://www.nuget.org/packages/Microsoft.WinForms.Designer.SDK

[amaitland]

Guidance on adding support seems to be limited, have created

• Designer SDK Runtime Dependencies dotnet/winforms#6757
• Designer OOP Debugging dotnet/winforms#6758

[amaitland]

Working branch https://github.com/cefsharp/CefSharp/tree/winforms/oopdesigner

Will wait to hear from the WinForms Team before progressing any further with this.

[goophps]

thank you

[amaitland]

Example of crash in #4148 (comment) when using designer.

Still no meaningful error message provided by the designer crash.

[amaitland]

Thanks to @davidei1955 for providing a link to a newer designer guide that was published a few months ago.

https://devblogs.microsoft.com/dotnet/custom-controls-for-winforms-out-of-process-designer/

There still isn't a newer SDK available and I was previously very reluctant to provide a dependency on a preview package. After extracting the designer Nupkg I can see it only includes ref assemblies so we should be able to use this as a development dependency (no direct reference will be added to the CefSharp nuget packages).

• Commit 1dc71ee adds reference to the new designer SDK.
• Additional refactoring in 1273afc to avoid referencing CefSharp.Core.Runtime.dll. (Change to P/Invoke)

There's some other code that can be converted to P/Invoke that might simplify designer support.

[amaitland]

Anyone wanting to test out the latest changes in relation to the WinForms OOP Designer can use the latest -CI build from https://www.myget.org/F/cefsharp/ (not the -RCI builds, they won't include the changes yet).

You should hopefully be able to add the ChromiumWebBrowser to a form using the designer, it will just say ChromiumWebBrowser if all goes well.

There's still likely issues. I still regularly see crashes with the WinForms OOP Designer with bare WinForms projects (no CefSharp references), so I suspect there are some issues that still need to be worked out.