Box :
=====

  Boxes represent (sub)processes. A box is a rectangular frame, which
may contain ports on its boundary (see help on <ObjectsEdit>:<Ports>).
 
  How to create a box:
1- select the <ObjectsEdit>:<Boxes>:<Create> menu function.
   ('b' is the keyboard short-hand)
2- drag the mouse left button for opposite corners in the drawing area.
Creation may fail for too small a size.

  Proper nesting of boxes, and absence of overlapping, is NOT checked
until explicit translation/completion is required by the user.

  Boxes can be reshaped or rescaled from any corner, using the
<ObjectsEdit>:<Boxes>:<Resize> functions.  Ports are projected
orthogonally.

 Box size attributes can be fixed by resources :
           atg*boxLineWidth: 3
           atg*boxMinWidth:  10
           atg*boxMinHeight: 10