Dragging an item over a nested ListView which is not a DropTarget will use it as target instead of parent

[Mertsch]

Repo:

1. Run Showcase.WPF.DragDrop.NET45 from https://github.com/Mertsch/gong-wpf-dragdrop

2. Select "Fixed #Issues"

3. Select Library throws "The specified Visual is not an ancestor of this Visual" #146

4. Drag and Drop an item from left to right

5. Select Dragging an item over a nested ListView which is not a DropTarget will use it as target instead of parent #244

6. Try to Drop an item from the left side onto the right side
   it only works when dropping onto the "Root" item
   Expected: It should also work on the inner "Item" box, as it is not marked as DropTarget and thus be ignored

[Mertsch]

@punker76 I am having some issues while verifying the fix, I can't point a finger on something specific, yet but it seems there is an issue with <UniformGrid/>

I have a ListView with an UniformGrid as ItemsPanel which leads to a horizontal first, then vertical layout. When there are no nested items the position is calculated perfectly and Drop targets the correct element.
When I Drag over the nested ListView with <StackPanel VerticalAlignment="Bottom"/>, which should be ignored, the target calculation for the UniformGrid is confused and DnD does not work or the target is a different item then the one dragged over.

@punker76 Have an idea what might be the cause?

[punker76]

@Mertsch That's really a special thing. Seems like you must implement your own DropTargetAdorner which handles the insertion (highlighting).