So how much killing of people is central enough for you? How much genocide?
Very non-radical actions you asking me to support.
From all of that I get that you're someone who thinks it's left Vs right. Two positions, Two ends of a line. If you're not at one end, you're at the other and what lies in-between (if anything) is grey, cowardly, compromising, compliant lemmings.
..and you're telling me to read books? This is the most juvenile and laziest of political thinking. You need to grow beyond thinking anyone that doesn't agree with you must either be the enemy or a collaborator. At least get past one-dimensional thinking.
And it's the Overton window (not "overtone") after Joseph Overton, a US libertarian and free-market supporter. He came up with the concept to describe how think-tanks should manipulate public opinion to consider what was previously unthinkable, particularly in a free-market direction. Of course, that's all lost now it's become part of pop-politics.