The current behavior is a hack to work around an implementation problem in the event bus of the WebProcessingUnit:
quoted from a correspondence with Web-UI team manager:
"This is a problem concerning the lack of PU-type in PU deployment.
In this case, the UI is unable to determine a proper location for the PU node in the application map graph.
After consulting with Uri on this, he suggested the following:
The GSM should attach a property to the context - in PU deployment time - containing the PU type name, to be read by the graph's layouter on PU added event fire, and not on first instance added event fire, as before."