WinForms Example - Add demo that reproduces #2928

Author: amaitland

CefSharp.WinForms.Example/CefSharp.WinForms.Example.csproj

@@ -99,6 +99,7 @@
     <Compile Include="InputBox.Designer.cs">
       <DependentUpon>InputBox.cs</DependentUpon>
     </Compile>
+    <Compile Include="Minimal\MultiFormAppContext.cs" />
     <Compile Include="Minimal\SimpleBrowserForm.cs">
       <SubType>Form</SubType>
     </Compile>

CefSharp.WinForms.Example/Minimal/MultiFormAppContext.cs

@@ -0,0 +1,36 @@
+// Copyright © 2019 The CefSharp Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+
+using System.Windows.Forms;
+
+namespace CefSharp.WinForms.Example.Minimal
+{
+    public class MultiFormAppContext : ApplicationContext
+    {
+        private SimpleBrowserForm form1;
+        private SimpleBrowserForm form2;
+
+        public MultiFormAppContext(bool multiThreadedMessageLoop)
+        {
+            form1 = new SimpleBrowserForm(multiThreadedMessageLoop);
+            form1.WindowState = FormWindowState.Normal;
+            form2 = new SimpleBrowserForm(multiThreadedMessageLoop);
+            form2.WindowState = FormWindowState.Normal;
+
+            form1.FormClosed += OnFormClosed;
+            form2.FormClosed += OnFormClosed;
+
+            form1.Show();
+            form2.Show();
+        }
+
+        private void OnFormClosed(object sender, FormClosedEventArgs e)
+        {
+            if (Application.OpenForms.Count == 0)
+            {
+                ExitThread();
+            }
+        }
+    }
+}