Re: Framework extending window functions for Follow Mode (etc.).

[martin rudalics]

> The six functions window-start, window-end, set-window-start, recenter,
> pos-visible-in-window-p, and move-to-window-line-function will acquire
> an extra optional parameter GROUP.  The notion is that "this call is
> interested in groups of windows, not just single ones".
>
> Each of these functions will get an associated variable, e.g.
> "window-start-function".  The function will call the value of that
> variable instead of doing its normal actions, when GROUP is non-nil.
> Typically, the `window-start-function' will recursively call
> window-start (on some window) to perform its operation.

Instead of an extra argument I would prefer to have these functions
check for the presence of a ‘window-start’, ‘window-end’, ... window
parameter just like ‘delete-window’ or ‘other-window’ do.

martin