Problematic overloaded "window" terminology

[hjoliver]

Fun with terminology 🤯

"Window" currently has two related but different meanings in Cylc 8:

• the active window of the workflow (i.e., the scheduler's "task pool")
  • (it can be loosely envisaged as a window of activity that moves along the graph)
• the graph-based window extent of the GUI, extending n edges out from "active" tasks
  • (this is genuinely a "window" on the workflow, in visualization terms)

Evidence suggests (recent Discourse post, and local user interactions) that this overloaded terminology is causing some confusion. E.g.:

• we say cylc remove "removes tasks from the active window"
• users may take this to imply that that removed task should disappear from the GUI (as it would do in Cylc 7, where the GUI could only show the "task pool")

It would be good to clear this up before documenting the hell out of cylc set etc.

Proposal

• refer to the scheduler task pool as the active tasks
  • or perhaps, the active task pool as a collective noun
• continue to refer to the GUI window as a graph-based window extending from the active tasks

[Note we kind of avoided using active tasks for this so far, because historically that meant tasks with active jobs. But a task isn't a job, so it's perfectly valid and easily explainable to define "active tasks" as those tasks currently being actively managed by the scheduler.]

[hjoliver]

Closing - at this point we have defaulted to using "active window" despite the potential for some confusion.