An operation may conditionally open a window etc.
Inform the user about error conditions and maybe let him choose, what to do.
Custom (?) progress feedback for actions, that may need > 2s.
The basic strategy is there, but I never made any detailed mind-simulation, so there're surely lots of details to work out remaining.
See also Interface | Skin.
Protection in model
Optimations [XXX ?]
E.g. objects/actions only available at certain state, e.g. storing of msg without recipient is possible, but not the action send.
Many representations (in skins) potentially depend on a locale. This applies especially text, but also icons (e.g. the 8-edged red STOP-icon) may be location-specific.
Ideally, we can treat all representations the same, i.e. consider all of them locale-dependant. Not sure, it that makes sense, however. No idea, how to negotiate the locale.