[Solved] Nested ContextMenu - Element is already the child of another element.

[Jay Sanderson]

I have a contextmenu nested inside a gridview.

<my:GridViewDataColumn.CellTemplate>
    <DataTemplate>
        <StackPanel Orientation="Horizontal">
            <TextBlock x:Name="txtStockName" Text="{Binding DisplayName}" Foreground="White">
                <telerik1:RadContextMenu.ContextMenu>
                    <telerik1:RadContextMenu x:Name="menu" Opened="RadContextMenu_Opened" ItemsSource="{Binding Path=AddToListMenuItems, Source={StaticResource stockSearchViewModel}}">
                    </telerik1:RadContextMenu>
                </telerik1:RadContextMenu.ContextMenu>
            </TextBlock>
        </StackPanel>
    </DataTemplate>
</my:GridViewDataColumn.CellTemplate>

The contextmenu is bound to a collection in the ViewModel.

I have added the following to the view code behind :

private void RadContextMenu_Opened(object sender, RoutedEventArgs e)

{

    try

    {

        RadContextMenu menu = (RadContextMenu)sender;

        GridViewRow row = menu.GetClickedElement<GridViewRow>();

        if (row != null)

        {

            row.IsSelected = row.IsCurrent = true;

            GridViewCell cell = menu.GetClickedElement<GridViewCell>();

            if (cell != null)

            {

                cell.IsCurrent = true;

            }

        }

        else

        {

            menu.IsOpen = false;

        }                

    }

    catch (Exception ex)

    {

          

        throw ex;

    }


I am finding that the menu works successfully the first time around, but on the second attempt I get the error -

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E; InfoPath.2; Media Center PC 6.0; OfficeLiveConnector.1.5; OfficeLivePatch.1.3)
Timestamp: Sun, 31 Oct 2010 10:35:21 UTC


Message: Unhandled Error in Silverlight Application
Code: 4004
Category: ManagedRuntimeError
Message: System.InvalidOperationException: Element is already the child of another element.
   at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   at MS.Internal.XcpImports.Collection_AddValue[T](PresentationFrameworkCollection`1 collection, CValue value)
   at MS.Internal.XcpImports.Collection_AddDependencyObject[T](PresentationFrameworkCollection`1 collection, DependencyObject value)
   at System.Windows.PresentationFrameworkCollection`1.AddDependencyObject(DependencyObject value)
   at System.Windows.Controls.UIElementCollection.AddInternal(UIElement value)
   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 unmanagedObj)

Line: 56
Char: 13
Code: 0
URI: http://localhost/DLTWeb/DLT.SLTestPage.aspx

Can someone give me some pointers as to where I'm going wrong ?

Kind Regards,

Jay Sanderson

[Maya]

Hi Jay Sanderson,

I tried to reproduce the issue you specified with the Mozilla browser, but I was not able to. I am sending you the sample project I test the problem on. Please take a look and let me know if there is some misunderstandings according to your requirements.

 
Kind regards,
Maya
the Telerik team

[Jay Sanderson]

Hi Maya,


Apologies for my delay in response. My problem is not so much with the Mozilla browser, I'm using this in IE.

I need to have a context menu that is databound to a collection outside of the data grid, which can pass a selected menu item, along with a selected grid item to a command property in the bound ViewModel.

This works with first selection/action using the code submitted in my first post, but causes the error on the second selection/action.

Cheers,,

Jay

[Maya]

Hi Jay Sanderson,

May you try to replicate your issue on the sample project I sent to you or sent your own sample application (via support ticket) ? Furthermore, why do you require to add your ContextMenu in the CellTemplate of the column ? You may try to add it to the rows as demonstrated in our demos.

Kind regards,
Maya
the Telerik team