The visual feedback when an artefact is being dropped as a child or to an
incompatible target should be improved. The explanation or error message could
be moved from top of the editor (editor assistant) closer to the drop target.
Also a visual aid that an element will be added as a child could be expressed.
Also this pattern could be reused accross all the editors (to be evaluated).
All the bulb messages and error messages that used to appear on top of the
namespace in the DV will now appear near the dropping location itself. Fixed on 9/13
There is still something to be fixed: If an element comes from a different file
and user tries to modify it, the message appears in the editor assitant, not on