Awesomium The specified name (external), is reserved. WebControl exception on WPF TabItem

Question

i am trying to create a simple WPF tabbed WebControl view using Awesomium 1.7.4.2. The idea is that I have a main ClosableTab (which extends TabItem) that contains a WebControl (let's say it HomeTab) which in turn loads a certain url. From HomeTab the user can open other tabs, ie each new web page opens at a new tab item wich contains a WebControl. Each WebControl has these handlers:

            webTabControl.CertificateError += webControl_CertificateError;
            webTabControl.NativeViewInitialized += webControl_NativeViewInitialized;
            webTabControl.ShowContextMenu += webControl_ShowContextMenu;
            webTabControl.LoadingFrameComplete += webControl_LoadingFrameComplete;
            webTabControl.LoadingFrameFailed += webControl_LoadingFrameFailed;

• On webControl_NativeViewInitialized I create a global javascript object called DotApi and then bind some javascript methods on it such as openTab.

• There is a method called JSHandler that handles the results of DotApi methods.

• When DotApi.openTab is called from HomeTab, a new tab is created, added in webTabControl (tab_control) and and then shown (if user clicked with left click).

• On tabItem_loaded a new webControl is created that binds the above webControl handlers and is added as content on TabItem.

• If user clicked with middle click, webControl.ApplyTemplate() is called (since middle clicks, open the new tabs in the background, ie the new TabItem doesn't get focused).

It seems quite straight-forward. This works fine almost every time. The problem is that one time in hundred it comes with this error:

The specified name (DotApi), is reserved. It either represents an HTML DOM object, or an object variable already available in the page. Use ExecuteJavascriptWithResult after DocumentReady, to obtain this object.
Parameter name: name

I noticed that the above error occurs only when the error below shows up:

A first chance exception of type 'System.ArgumentException' occurred in Awesomium.Windows.Controls.dll

I looked at debug.log and noticed that this error is similar to my error with the only difference on the specified name:

The specified name (external), is reserved. It either represents an HTML DOM object, or an object variable already available in the page. Use ExecuteJavascriptWithResult after DocumentReady, to obtain this object.
Parameter name: name

My questions are:

- Why this error occurs so rarely?

- How can it be fixed?

Below is sample code to help you understand the flow:

webControl_NativeViewInitialized

  private void webControl_NativeViewInitialized(object sender, WebViewEventArgs e)
        {
            WebControl wbControl = sender as WebControl;
            try
            {
                JSObject jsobject = wbControl.CreateGlobalJavascriptObject("DotApi");
                // openTab will be invoked each time a new page opens in new tab
                jsobject.Bind("openTab", false, JSHandler);
            }
            catch (Exception ex)
            {
                Debug.WriteLine("NativeViewInitialized exception: " + ex.Message);
            }
        }

JSHandler

        private void JSHandler(object sender, JavascriptMethodEventArgs args)
        {
            try
            {
                if (!args.MustReturnValue)
                {
                     case @"openTab": // parameters: url, type(order,index,map), true/fasle(focus on new tab),arguments 
                            if (args.Arguments.Length > 0)
                            {
                                Application.Current.Dispatcher.BeginInvoke(
                                        new OpenNewTabDelegate(OpenNewTab), args.Arguments);
                            }
                            break;
                }
            }
            catch (Exception e)
            {
                MessageBox.Show("JSHandler Exception: " + e.Message);
            }
        }

OpenNewTab

        private void OpenNewTab(JSValue[] arguments)
        {
            try
            {
                ClosableTab theTabItem = new ClosableTab(this);
                theTabItem.Title = "Loading";

                theTabItem.Loaded += (s_, e_) => theTabItem_Loaded(theTabItem, e_, arguments);

                tab_control.Items.Add(theTabItem);
                if (!(bool)arguments[2])  // whether it focus on new window or not
                {
                    theTabItem.Focus();
                }
            }
            catch (Exception e)
            {
                Debug.WriteLine("OpenNewTab exception e: " + e.Message);
            }            
        }

theTabItem_Loaded

        private void theTabItem_Loaded(object sender, RoutedEventArgs e, JSValue[] arguments)
        {
            ClosableTab currentTab = sender as ClosableTab;
            currentTab.Loaded -= (s_, e_) => theTabItem_Loaded(currentTab, e_, arguments);

            WebControl webTabControl = new WebControl();

            webTabControl.Source = new Uri((string)arguments[0]);
            webTabControl.CertificateError += webControl_CertificateError;
            webTabControl.NativeViewInitialized += webControl_NativeViewInitialized;
            webTabControl.ShowContextMenu += webControl_ShowContextMenu;
            webTabControl.LoadingFrameComplete += webControl_LoadingFrameComplete;
            webTabControl.LoadingFrameFailed += webControl_LoadingFrameFailed;
            currentTab.Content = webTabControl;

            webTabControl.Dispatcher.BeginInvoke(new Action(() =>
            {
                    // Load the webcontrol in the backgound
                    if(!currentTab.IsSelected){
                        webTabControl.ApplyTemplate();
                    }
                }));
        }

Answer 1

After debugging i figured out that it was a timedOut exception from awesomium. To handle it, each time i create a webControl i set its property: SynchronousMessageTimeout = 0. If you don't set it to 0 the default value will be 800ms according to current documentation SynchronousMessageTimeout

This prevented the below exceptions from appearing:

A first chance exception of type 'System.ArgumentException' occurred in Awesomium.Windows.Controls.dl

The specified name (DotApi), is reserved. It either represents an HTML DOM object, or an object variable already available in the page. Use ExecuteJavascriptWithResult after DocumentReady, to obtain this object.
Parameter name: name