[Solved] Null Reference with Docking

[Brett]

I'm getting the following error when using a docking panel.

Unhandled Error in Silverlight Application
Code: 4004   
Category: ManagedRuntimeError      
Message: System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.Windows.Controls.RadPaneGroup.OnIsInDocumentHostChanged(Boolean oldValue, Boolean newValue)
   at Telerik.Windows.Controls.RadPaneGroup.Telerik.Windows.Controls.Docking.IDocumentHostAware.set_IsInDocumentHost(Boolean value)
   at Telerik.Windows.Controls.RadSplitContainer.PrepareContainerForItemOverride(DependencyObject element, Object item)
   at System.Windows.Controls.ItemsControl.MS.Internal.Controls.IGeneratorHost.PrepareItemContainer(DependencyObject container, Object item)
   at System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.PrepareItemContainer(DependencyObject container)
   at System.Windows.Controls.ItemsControl.AddVisualChild(Int32 containerIndex, DependencyObject container, Boolean needPrepareContainer)
   at System.Windows.Controls.ItemsControl.AddContainers()
   at System.Windows.Controls.ItemsControl.RecreateVisualChildren(IntPtr nativeItemsControl) 

Here is a copy of the xaml code that throws the error, the code is inside of a grid:

<telerik:RadDocking   BorderThickness="0" Padding="0">
            <telerik:RadDocking.DocumentHost>
                <telerik:RadSplitContainer>
                    <telerik:RadPaneGroup>
                        <telerik:RadMap x:Name="xMap" Height="600" InitializeCompleted="xMap_InitializeCompleted" MouseClickMode="None">
                            <telerik:InformationLayer x:Name="InformationLayer2"
                                    AllowDataTemplateForZoomLevel="True"
                                    Visibility="Collapsed" ItemTemplate="{StaticResource ZonePointTemplate}"/>
                            <telerik:InformationLayer x:Name="InformationLayer1"
                                      AllowDataTemplateForZoomLevel="True"
                                      Visibility="Collapsed"/>
                        </telerik:RadMap>
                    </telerik:RadPaneGroup>
                </telerik:RadSplitContainer>
            </telerik:RadDocking.DocumentHost>

            <telerik:RadSplitContainer InitialPosition="DockedLeft">
                <telerik:RadPaneGroup>
                    <telerik:RadPane Header="Search Tools" IsPinned="True">
                        <TextBlock Text="Search Tools" />
                    </telerik:RadPane>
                    <telerik:RadPane Header="Map Options" IsPinned="True">
                        <TextBlock Text="Map Options" />
                    </telerik:RadPane>
                    <telerik:RadPane Header="Routing" IsPinned="True">
                        <TextBlock Text="Routing" />
                    </telerik:RadPane>
                </telerik:RadPaneGroup>
            </telerik:RadSplitContainer>

            <telerik:RadSplitContainer InitialPosition="DockedRight">
                <telerik:RadPaneGroup>
                    <telerik:RadPane Header="Truck Information" IsPinned="False">
                        <TextBlock Text="Truck Information" />
                    </telerik:RadPane>
                </telerik:RadPaneGroup>
            </telerik:RadSplitContainer>
        </telerik:RadDocking>

Could someone please help me find the problem with the XAML.

Thanks for you help!

[Vladi]

Hello,

It looks like you have added the RadMap control directly to the RadPaneGroup which is causing the described exception. In order to place content in any RadPaneGroup it needs to be wrapped by a RadPane.

The next code snippet shows how the RadDocking should be declared:

<telerik:RadDocking ...>
    <telerik:RadDocking.DocumentHost>
        <telerik:RadSplitContainer>
            <telerik:RadPaneGroup>

                <telerik:RadPane>

                    <telerik:RadMap ...>
                    </telerik:RadMap>

                </telerik:RadPane>

            </telerik:RadPaneGroup>
        </telerik:RadSplitContainer>
    </telerik:RadDocking.DocumentHost>
    ...
</telerik:RadDocking>

Regards,
Vladi
Telerik