Exception when setting HtmlSource

[Alan Sauls]

I have downloaded the trial version of the Silverlight controls.  I am using Visual Studio 2010 and Silverlight 4.
When I add the same code that is in the provided example when I set the HtmlSource I get the following exception:

System.NullReferenceException was unhandled by user code
  Message=Object reference not set to an instance of an object.
  StackTrace:
       at Telerik.Windows.Controls.RadHtmlPlaceholder.get_RootHtmlElement()
       at Telerik.Windows.Controls.RadHtmlPlaceholder.SetContentOverflow()
       at Telerik.Windows.Controls.RadHtmlPlaceholder.OnSourceHtmlChanged()
       at Telerik.Windows.Controls.RadHtmlPlaceholder.OnSourceHtmlPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
       at Telerik.Windows.PropertyMetadata.<>c__DisplayClass1.<Create>b__0(DependencyObject d, DependencyPropertyChangedEventArgs e)
       at System.Windows.DependencyObject.RaisePropertyChangeNotifications(DependencyProperty dp, Object oldValue, Object newValue)
       at System.Windows.DependencyObject.UpdateEffectiveValue(DependencyProperty property, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, ValueOperation operation)
       at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value, Boolean allowReadOnlySet)
       at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
       at Telerik.Windows.Controls.RadHtmlPlaceholder.set_HtmlSource(String value)
       at Bowne.XBRL.XBRLProcessor.MainPage.treeViewHeadings_SelectedItemChanged(Object sender, RoutedPropertyChangedEventArgs`1 e)
       at System.Windows.Controls.TreeView.OnSelectedItemChanged(RoutedPropertyChangedEventArgs`1 e)
       at System.Windows.Controls.TreeView.ChangeSelection(Object itemOrContainer, TreeViewItem container, Boolean selected)
       at System.Windows.Controls.TreeViewItem.Select(Boolean selected)
       at System.Windows.Controls.TreeViewItem.OnGotFocus(RoutedEventArgs e)
       at System.Windows.Controls.Control.OnGotFocus(Control ctrl, EventArgs e)
       at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, String eventName)

Any ideas what is causing this?

[Valentin.Stoychev]

Hi Alan Sauls,

I tested your scenario and it works on our end. Please find attached project.

Let us know if there is anything specific related in your scenario.

Greetings,
Valentin.Stoychev
the Telerik team

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[Alan Sauls]

Thanks for the prompt reply.  I solved it.  Although I had set windowless to true in my aspx file in my Web project(host for Silverlight control), during debug I was generating a temp html file(the default setting) which did not have windowless set to true.  After setting this to use a permanent file that I specify, it all worked correctly.