Multiple AppDomains error "Cannot pass a GCHandle across AppDomains".

Hey team,

I recently stumbled upon this pretty nasty gotcha when trying to host our browser control inside a plugin system that loads a new AppDomains per plugin. When the native libcef.dll makes a call back into managed there is an exception thrown "Cannot pass a GCHandle across AppDomains".

I found that there have been several post written about this problem-
http://lambert.geek.nz/2007/05/29/unmanaged-appdomain-callback/
http://www.lenholgate.com/blog/2009/07/error-cannot-pass-a-gchandle-across-appdomains.html

Highlight from these posts-
"Consequently, when calling managed code from unmanaged code, the compiler has to pick one AppDomain to use, and it appears to pick the first one."

To test this issue

Create a new WPF application
Change App.xaml Build Action to Page (right-click Properties->Build Action->Page)
Add file below with main - Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using CefSharp;

namespace MultipleAppDomains
{
    class Startup
    {
        [STAThread()]
        static void Main()
        {
            AppDomain domain = AppDomain.CreateDomain("another domain");
            CrossAppDomainDelegate action = () =>
            {
                var settings = new CefSettings
                {
                    RemoteDebuggingPort = 8088,
                    BrowserSubprocessPath = "CefSharp.BrowserSubprocess.exe",
                    LogSeverity = LogSeverity.Verbose

                };

                if (!Cef.Initialize(settings))
                {
                    // Do Something
                }
                App app = new App();
                app.MainWindow = new MainWindow();
                app.MainWindow.Show();
                app.Run();
            };
            domain.DoCallBack(action);
        }
    }
}

I'd like to get the discussion going and come up with a good course of action.