In the chilly climes of the upper part of Michigan's lower peninsula Joe Overton has the kind of job that gives him the time to think.Actually, he works for a Think Tank.This is his idea: Politicians can only voice opinions within a band from left to right that falls within the political spectrum. To voice opinions outside the acceptable is to invite disaster and possible defeat. Working within the window a politician can be pretty sure that nothing he has said will get him condemned by the populace..Along comes Donald Trump.He seems to be giving voice to all sorts of things outside the window. He should be roundly chastized by the populace because what he is saying proves that he is not "Presidential."However, what the current pot of pols fail to recognize is that the Overton Window has shifted, making all those no-no opinions acceptable, even desirable.Trump recognized the shift and used it with a joyful vivacity. What he realized was that certain "down and dirty" phrases and expressions were now common usage, expressed freely by most people and no longer shocking, except to his opponents. They are still mumbling over the fact that his words are unacceptable. Maybe that was true as late as 1990, but not today..