Binding to CheckState with Toggle.On throws exception

2 posts, 0 answers
  1. mckhendry
    mckhendry avatar
    2 posts
    Member since:
    Jun 2010

    Posted 11 Mar 2012 Link to this post

    Using the TreeView, I want to have a list of items that can be checked and reordered. I'm using an ItemContainerStyle for binding the CheckState, and a Converter to convert to/from a bool value in my viewmodel. The issue I'm having is when loading the list where some of the items should be defaulting to a CheckState of Toggle.On. If all items have a CheckState of Toggle.Off then there is no exception.

    The details of the exception are as follows:

    Microsoft JScript runtime error: Unhandled Error in Silverlight Application Object reference not set to an instance of an object. at Telerik.Windows.Controls.TreeView.WeakReferenceKey`1..ctor(T item)
    at Telerik.Windows.Controls.RadTreeView.StoreCheckState(RadTreeViewItem container, Object item, ToggleState newCheckState)
    at Telerik.Windows.Controls.RadTreeViewItem.OnCheckStatePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
    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.InvalidateProperty(DependencyProperty property)
    at MS.Internal.FrameworkCallbacks.InvalidateProperty(IntPtr nativeTarget, UInt32 propertyId)

    I've created a sample project which easily reproduces this issue (click on the second button to see the exception), and can be downloaded from

    NOTE: I've been able to recreate this issue with the following releases:

    I'm unsure of how to fix this, or what method should be used instead.

    Kelly White - Microsoft MVP Windows Phone Development
  2. Hristo
    Hristo avatar
    352 posts

    Posted 13 Mar 2012 Link to this post


    I'm posting my reply to your support ticket in this forum thread because other other users could find it useful too:

    There is an issue with Telerik RadTreeView when using style bindings to CheckState in Silverlight. We've already addressed that issue and will try to provide a fix ASAP. You can track the related item in our public issue tracking system (PITS) and vote for its resolution via following page: 

    Also, I've modified your example to use ContainerBindings instead. I'm using your DLLs version and everything seems correct.
    Finally, I would like to advise you not to use CheckState bindings and build in tri-state functionality. In that case the bindings take precedence over the tri-state logic which could be unexpected in some scenarios. Instead, the best bug-free approach in my personal opinion would be to implement the tri-state logic by yourself inside the view model.

    the Telerik team
    Sharpen your .NET Ninja skills! Attend Q1 webinar week and get a chance to win a license! Book your seat now >>
Back to Top