WPF - ItemTemplate not acting as expected

Question

I have a UserControl which I\'m using to display a list of UIElements. The control consists of a single ItemsControl with it\'s

Answer 1

If you set the DataType property on the DataTemplate it would start working.

Answer 2

It's because it's a list of UIElement, the item template is only applied if the items can't be displayed directly.

Answer 3

Nir is right, this custom ItemsControl implementation will solve the issue and let use your own ItemTemplate:

public class ItemsControlForUIElement : ItemsControl
{
   protected override DependencyObject GetContainerForItemOverride()
   {
       return new ContentPresenter();
   }
   protected override bool IsItemItsOwnContainerOverride(object item)
   {
       return false;
   }
}

Answer 4

Nir is correct, ItemsControl will add item directly to its Panel if they are UIElements. I couldn't find any mention of this behavior in MSDN, but Dr. WPF mentions it in his article on item containers:

If a UIElement is added to the Items collection of an explicit ItemsControl instance (as opposed to an instance of a derived class like ListBox), it will become a direct child of the items panel. If a non-UIElement is added, it will be wrapped within a ContentPresenter.

Your solution is probably to use a ListBox instead, and set ItemContainerStyle to a new Style for ListBoxItem, and in that style, use a ControlTemplate with your Border in it.

Answer 5

Robert Macnee nailed the reason on the head. His solution involves using the control template which might be overkill for a given scenario. Alternatively, use a ListBox - set the ItemContainerStyle to a new Style for ListBoxItem, and in that style, set the ContentTemplate to the DataTemplate that you wanted to use in the ListBox ItemTemplate.