Items in a list have context menus. The context menu items are bound to routed commands.
The context menu items work correctly if the list control is a ListBox, but as soon as I downgrade it to an ItemsControl it no longer works. Specifically the menu items are always greyed out. The CanExecute callback in my CommandBinding is not being called either.
What is it about ListBox that allows context menu items with commands to bind correctly?
Here are some excerpts from a sample app I put together to highlight the problem:
<!-- Data template for items -->
<DataTemplate DataType="{x:Type local:Widget}">
<StackPanel Orientation="Horizontal">
<StackPanel.ContextMenu>
<ContextMenu>
<MenuItem Header="UseWidget"
Command="{x:Static l:WidgetListControl.UseWidgetCommand}"
CommandParameter="{Binding}" />
</ContextMenu>
</StackPanel.ContextMenu>
<TextBlock Text="{Binding Path=Name}" />
<TextBlock Text="{Binding Path=Price}" />
</StackPanel>
</DataTemplate>
<!-- Binding -->
<UserControl.CommandBindings>
<CommandBinding Command="{x:Static l:WidgetListControl.UseWidgetCommand}"
Executed="OnUseWidgetExecuted"
CanExecute="CanUseWidgetExecute" />
</UserControl.CommandBindings>
<!-- ItemsControl doesn't work... -->
<ItemsControl ItemsSource="{Binding Path=Widgets}" />
<!-- But change it to ListBox, and it works! -->
<ListBox ItemsSource="{Binding Path=Widgets}" />
Here's the C# code for the view model and data item:
public sealed class WidgetListViewModel
{
public ObservableCollection<Widget> Widgets { get; private set; }
public WidgetViewModel()
{
Widgets = new ObservableCollection<Widget>
{
new Widget { Name = "Flopple", Price = 1.234 },
new Widget { Name = "Fudge", Price = 4.321 }
};
}
}
public sealed class Widget
{
public string Name { get; set; }
public double Price { get; set; }
}
Here's the C# code-behind for the control:
public partial class WidgetListControl
{
public static readonly ICommand UseWidgetCommand
= new RoutedCommand("UseWidget", typeof(WidgetListWindow));
public WidgetListControl()
{
InitializeComponent();
}
private void OnUseWidgetExecuted(object s, ExecutedRoutedEventArgs e)
{
var widget = (Widget)e.Parameter;
MessageBox.Show("Widget used: " + widget.Name);
}
private void CanUseWidgetExecute(object s, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
e.Handled = true;
}
}
Just to reiterate the question -- what is is that ListBox provides that allows for it's context menu item commands to bind correctly, and is there some way I can get this working for ItemsControl?