@simulo I recall particularly the distinctions in Tidwell's UI pattern language around transient posture UI (a helper for tasks, like an arithmetic calculator or glyph lookup) versus sovereign posture UI (dense and designed to be worked with, using most of the user's attention; spreadsheets, perhaps, or computer aided mechanical design). Different contexts of interaction drove different solution patterns
There seems to be productive overlap between Tidwell's application postures and Cooper personas for who needs what from UI, for what purpose in what context. The famous example demonstrating Cooper personas was the design of an airline in-flight entertainment system before everyone started bringing their own devices.