Created attachment 184251 [details]
test slide

In Impress / Draw, since the fix for bug 145359, we can drag and drop objects in and out of groups.
However, dropping into the empty area under the last element in the tree doesn't do anything.

Steps:
1. Open attachment
2. Open navigator sidebar
3. Drag and drop Shape 2 in the empty area below Shape 4

Result:
A green line appears under the last item, but nothing happens when Shape 2 is dropped.

Expected:
Object is placed last, at the same level as the item below which it is placed (in this case, ungrouped. If Shape 4 was part of a group, Shape 2 would enter the group.)