Mouser, I didnt think about that. Looks like a good solution. The logical next step would be to let users set various key processes as automatic triggers for specific "process priority configurations" (config files). Quite like what steeladept has advised but instead of setting every processes to idle (which could be catastrophic in case the of cooperating processes, bandwich shaping tools, firewalls or hamachi) let users to design their own config files.

The problem is when we have more than one key process working at the same time. The simplest solution might be that every time a new key process appears it overrides the previous configuration. I think it's more than a sufficient solution. Superimposing priority classes or increasing the priority of the focused process on top of that would be kind of like mind modelling which would lead us straigh into the domain of consciousness.  :o ;D