To give another example: A scrollbar is defined mostly by its action
to "scroll content in the associated window". Of course you could use
the scrollbar widget just as well to adjust your speaker volume, but
then it wouldn't be a scrollbar, even if it looked like one.
There is a task in etc/TODO:
** Compilation error navigation bar, parallel to the scroll bar,
indicating where in the buffer there are compilation errors.
Perhaps we could arrange to display these error indications on top
of the scroll bar itself. That depends on to what extent toolkit
scroll bars are extensible.
If it's possible to display such tab-like indications
on the scroll bar, is it still called a scroll bar?
If it's not possible, then what is an alternative?
Maybe, 1-column side bar windows?