Feature request: Scrollbar for Check

[lelutin]

It would be great to be able to scroll through a mult-choice list (a Check).

A simple implementation would be to add a new class for this functionality.

However, I believe another way is possible:

In the current code, Scrollbar is pretty much like a glorified Bullet. It does the same but adds scrolling and scrollbar indicators. So I would argue that Scrollbar could instead wrap around another class like Bullet and trigger the underlying key actions for space and enter keys (with the differentiated index wrt scrolling position) but add functionality to display only a portion of items and scrollbar indicators.

If Scrollbar was implemented this way, then it would be possible to also wrap around a Check class without adding much to the Scrollbar class itself.

Yet another way to approach this would be to flip things around and implement list displaying and navigation (with possibility of scrolling) in a base class that both Bullet and Check then would inherit. This approach would be imho the cleanest and most clever. However, it would have a bigger impact on the API of this library (e.g. using Scrollbar directly would not be meaningful anymore).