Complete the investigation and turn the solution into a generic
mix-in-template, which can be used in flexible ways to support
this qualifier notation.
Moreover, recapitulate requirements for the ElementBoxWidget
- most notably the NOBUG logging flags have been renamed now
- but for the configuration, I'll stick to "GUI" for now,
since "Stage" would be bewildering for an occasional user
- in a similar vein, most documentation continues to refer to the GUI
this is the entry point into the section holding the various
design documents -- we try to separatte conceptual/design
from the actual technical documentation
