Open sourcing windows probably would be so difficult that you could consider it a nearly impossible task. Over 40 years of licensing and patent agreements with

Open sourcing windows probably would be so difficult that you could consider it a nearly impossible task. Over 40 years of licensing and patent agreements with thousands of companies and institutions with the unavoidable flux of acquisitions, merges and deaths, big customer agreements. You'll need an army of lawyers and sizable team of developers working in a multi-year project to secure all the paperworks and sanitize the code where you couldn't reach an agreement with the other party.