Application using Delphi runtime with Virtual-TreeView module, like xEdit, pass a NULL IDropSource to SHDoDragDrop, prevnting the drag and drop to works at all, when used in Windos Vista and above compatiblity mode, while windows xp compatibility mode works (as it use a dfferent system). Documentation stated that Windows Vista and above will create an internal IDropSource in this case. Creating a dummy IDropSource with minimal functionality allow the drag and drop to works using the default cursor. In case of xEdit it won't show the cell that it's being dragged like on windows, a functionality that require a full implementation of IDropSource::GiveFeedback and DragSourceHelper2::InitializeFromBitmap.
Solve the functional part of #54923
I'm unsure on how to write tests for this.
-- v3: shell32: Create an internal IDropSource in SHDoDragDrop if it wasn't passed by the caller