The Overton Window of public discourse

At a dinner party last night, I was introduced to the idea of the Overton Window, a concept in political theory (also known as the "window of discourse") that posits a kind of window or range of political discourse that a democratic society deems acceptable at any one point in time.
The idea is far from new, but political scientist Joseph P. Overton visualized a kind of scale from policy to popular to sensible to acceptable to radical to unthinkable, a scale that runs in two directions along a spectrum from "more free" to less free". A political idea has to find itself in a widow within the acceptable range, based on the current climate of public opinion. Any ideas outside that range may be considered too extreme for a politician to either gain or hold office. Others, however, may seek to move or widen that window so that ideas currently deemed unacceptable move more into the range of acceptable discourse.
The obvious example of all this is the way that some of Donald Trump's more outré ideas and attitudes have change the perception among many people of what is considered reasonable, both in terms of policy and behaviour. It came up in our conversation in the context of Alexandria Ocasio-Cortez and the New Green Deal. By putting forward such an apparently extreme set of ideas (at least in the current Trump-driven political climate), the Democrats are attempting to shift the range of acceptable topics of political discourse and acceptable policies leftward, in order to correct the extreme rightward lurch that Trump has occasioned.
Interesting stuff.