No support for derived item container classes

[punker76]

Original author: Jan_Waec...@gmx.de (January 16, 2011 15:53:40)

I have a ListBox which uses a custom item container class (derived from ListBoxItem). After enabling drag and drop for this ListBox (using dd:DragSource = "true" dd:DropTarget = "true") selecting any item was not possible anymore.

The problem is caused by, GetItemContainer not finding my custom derived item container class.

I'd recommend changing GetVisualAncestor not to use "==" for type checking, but using something which is comparable to the "is" operator:

public static DependencyObject GetVisualAncestor(this DependencyObject d, Type type)
{
    DependencyObject item = VisualTreeHelper.GetParent(d);

    while (item != null)
    {
        if (item.GetType() == type ||
            item.GetType().IsSubclassOf(type)) 
            return item;
        item = VisualTreeHelper.GetParent(item);
    }

    return null;
}

After this change the problem is gone.

Original issue: http://code.google.com/p/gong-wpf-dragdrop/issues/detail?id=30

[punker76]

will be supported in 0.1.3.9