<idle> and <status> ignored in "unavailable" presences
Title mostly says it all. In the roster view, on the tooltip, gajim can show both the "Last Interaction in Presence" (XEP-0319) and the presence status, except if the presence type=unavailable.
By the way, it would be awesome that the "Last Interaction in Presence" info was more easy to see in the UI, since this is more or less the "modern" way of displaying presences in IM, which makes sense in a context where most users connect via mobile phones.