RE: Improving browsing and discoverability in the Packages Menu

[Drew Adams]

> Ability to handle trees within tabulated lists would be nice. An
> intermediate solution that might be quicker to build would be dired-
> like marking by regexp and hiding/exposing.

Not just intermediate, but better, IMO.

Markings can be used for lots of things, just as they are in Dired.

Currently, IIUC, the `list-packages' UI provides only for markings
that mean "install" and "delete".  A more general marking facility,
a la Dired, would be an improvement, and would invite future
enhancements that use the same (and familiar) UI.