I can't find it again, but somewhere around here someone was asking for more detail in moving matter and energy around between containers. I believe the response was something along the lines of "that wouldn't work well with the UI", but after running around a little more I'm thinking of one additional function that would help:
A button that adds matter/energy from the container/battery you're standing on, analogous to doomRL's "take ammo out of weapon on floor" command. Or possibly even make it the default when you step on a filled container, maybe.
I don't see a huge problem with allowing you to automatically pick up the contents, although this would enable you to forgo the attachment cost. Anyone else have an opinion on this? It might be bothersome if you're trying to keep a full container on the ground for some reason and accidentally step on it, but I imagine that would be quite rare.
(I definitely wouldn't add a dedicated command for it--too specific--but if automatic we wouldn't need one, anyway.)
Along with this, let us see if the containers on the floor have anything in them before picking them up, at least when adjacent to them. (Long distance could be an added perk of one of the scan tools?). Since they do seem to be spawned with contents frequently, and having to pick them all up to check is a little unwieldy.
You can already do this, from any range. Open the info window for the part and it will display the contained amount next to its name.
Since it was convenient while looking into this, I've also just now added that same information to appropriate the map labels themselves, so expect to see it in Alpha 4
Theoretically it will also display in the Scan window as well, but their names are often too long to fit, so it will get cut off since it's at the end.