ContextMenu - Build Dynamically SubMenu - AG_E_UNKNOWN_ERROR [Line: 1 Position: 1449]

[Pinho]

Hi,

 I've got a sub menu (inside a context menu) that is being built dinamically.
 If I've the context menu open or it was open before, and if I try to clear all menu items of the sub menu or try to add a new sub menu, I get an exception:

 AG_E_UNKNOWN_ERROR [Line: 1 Position: 1449]

I define a context menu and I set it to open with:

contextMenu.EventName = "MouseLeftButtonDown";




It's defined for a image:

<Image x:Name="imgSearch" HorizontalAlignment="Center" Source="/AssemblyName;component/Images/selection-arrow-16x16.png" Height="16" Width="16" Margin="0,2,2,2" Cursor="Hand">
                <telerikNavigation:RadContextMenu.ContextMenu>
                    <telerikNavigation:RadContextMenu x:Name="contextMenu" ModifierKey="None" Background="White" Opened="contextMenu_Opened">
                        <telerikNavigation:RadMenuItem Header="Find" Click="RadMenuItem_Click">
                            <telerikNavigation:RadMenuItem.Icon>
                                <Image Width="16" Height="16" Source="/AssemblyName;component/Images/Magnifier-16x16.png"/>
                            </telerikNavigation:RadMenuItem.Icon>
                        </telerikNavigation:RadMenuItem>
                        <telerikNavigation:RadMenuItem Header="Simple Query" Click="RadMenuItem_Click">
                            <telerikNavigation:RadMenuItem.Icon>
                                <Image Width="16" Height="16" Source="/AssemblyName;component/Images/Help-16x16.png" />
                            </telerikNavigation:RadMenuItem.Icon>
                        </telerikNavigation:RadMenuItem>
                        <telerikNavigation:RadMenuItem x:Name="radMenuItemSavedQueries" Header="Stored Queries" Background="White">
                            <telerikNavigation:RadMenuItem.Icon>
                                <Image Width="16" Height="16" Source="/AssemblyName;component/Images/save-blue-16x16.png" />
                            </telerikNavigation:RadMenuItem.Icon>
                        </telerikNavigation:RadMenuItem>
                    </telerikNavigation:RadContextMenu>
                </telerikNavigation:RadContextMenu.ContextMenu>
            </Image>

I go to a db get some values to fill the submenu that I fill in a callback (async. get):

RadMenuItem menuItem = new RadMenuItem();
foreach (Object result in results)
{
    menuItem = new RadMenuItem() { Header = result.Name, Name = result.Name };
    menuItem.Click += new RoutedEventHandler(RadMenuItem_Click);
    try
    {
        radMenuItemSavedQueries.Items.Add(menuItem);
    }
    catch (Exception ex)
    {
      Console.Write(ex.Message);
    }
}

Is there anything I am doing wrong? How should this be done?

Thanks for the help,

L. Pinho

[Valeri Hristov]

Hi Luis,

The easiest workaround for this problem is to avoid clearing all MenuItem sub-items when the MenuItem has an image:
// Store the count of the original items in order to be able to remove them later
int originalItemsCount = radMenuItemSavedQueries.Items.Count;

// Add the new items here
RadMenuItem menuItem = new RadMenuItem();
foreach (Object result in results)
{ 
    menuItem = new RadMenuItem() { Header = result.Name, Name = result.Name }; 
    menuItem.Click += new RoutedEventHandler(RadMenuItem_Click); 
    try 
    { 
        radMenuItemSavedQueries.Items.Add(menuItem); 
    } 
    catch (Exception ex) 
    { 
        Console.Write(ex.Message); 
    }
}

// Remove the original items
for (int i=0; i<originalItemsCount; i++)
{
    radMenuItemSavedQueries.Items.RemoveAt(0);
}

The problem is related to a bug in the Silverlight 2 Control class, which does not clear the TemplateBinding in the control template when it is changed. Since RadMenuItem changes its template depending on the count of its items - when there are no items a different template is used, there is a moment where the MenuItem Icon becomes with two parents, hence the exception.

As far as I know, in Silverlight 3 this bug is fixed, but we will look for a workaround in our controls in case there is strong demand for Silverlight 2 versions after the Silverlight 3 release.

Regards,
Valeri Hristov
the Telerik team

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[Pinho]

Hi Valeri,

 when I do the 1st add, the exception is throwned, from what I can see, if I open the context menu once, before being fully build, when I try to add the sub menu is throws an exception.

 My workaround was to add a item in xaml (Please wait... Menu being built) and then remove this extra item as you state in your code.

I think this might be an issue, but your workaround helped me enough, thanks

L. Pinho

[Jamest]

Just an FYI to this thread, I am using SL3 and I am still experiencing this issue with an exception thrown when dynamically clearing/adding sub items when the root menu item has an icon set in xaml. I removed the icon definition from xaml and set it the icon in code and the exception is no longer thrown.