Port :
======

  Ports represent communication gates. They are represented as circles
on boxes.

   How to create a port:
1- select the <ObjectsEdit>:<Ports>:<Create> menu button
   ('p' is the keyboard short-hand)
2- click with the mouse left button inside the desired box. The
   port will be placed at the nearest projected location on the
   box boundary.

   Ports can be connected together either:
- graphically, by edges and possibly "webs" for multisynchronisations
- textually, by label identifications. See help <Options>:<Web fusion
by name on/off>.

   Ports are selected/moved/killed along with their box. They can also
be moved on the box surface or killed independently.

 Port size attributes can be fixed by resources:
        atg*portRadius : 5
        atg*portLineWidth: 0 (default, uses fast raster)