Get all descendent DependencyObjects of a DependencyObject.

VisualTreeHelperAddition.cs

public static class VisualTreeHelperAddition
{
	public static IEnumerable<T> GetDescendents<T>(this DependencyObject parent) where T : DependencyObject
	{
		if (parent == null)
			yield break;

		for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
		{
			var child = VisualTreeHelper.GetChild(parent, i);
			if (child is T)
			{
				yield return (T)child;
			}

			// Return grandchild recursively.
			foreach (T grandchild in GetDescendents<T>(child))
			{
				yield return grandchild;
			}
		}
	}
}