I think there might be a small misunderstanding. When using the normal area selection window, the AttributeElementContainer does not appear in the output, even though "you just get everything that is in the raised window.". It only shows up when selecting elements individually using the Sum Function. So the same objects, selected two different ways, produce different output. That's what I'd consider the actual "weird behaviour" here. When it would be the other way around I would understand your point.

As for simply not using the Sum Function: depending on the script, being able to aggregate a selection that way can actually be quite useful. Ruling it out isn't really practical. For example in my current case I use it to change the height of a lot of columns, and I often only want to edit certain ones.

That said, I'm genuinely curious, is there an intended use case for the AttributeElementContainer in Visual Scripting?
And if it's intended to show up, shouldn't it always be attached to the element?

question answer: yes, I activate the Sum Function while the SelectByAreaInput node is active.

I'd genuinely like to understand your perspective better, since you clearly have much more experience with Allplan's internals than I do. Why exactly is this considered the wrong way to use it? The Sum Function is actually available and usable while this node is active, and as far as I can tell there is no way to suppress or disable it. That makes it look to me like it is intentionally supported for this type of selection, which is part of why the inconsistent output surprised me.

Regarding the AttributeElementContainer, I may well be missing something about how Allplan handles this internally. But from what I observe, each column has its own individual AttributeElementContainer attached to it. And it always appears in the output when using the Sum Function(right click before selecting), regardless of whether I draw an area or click each column individually. The only case where it does not show up is when using the normal area selection without the Sum Function. That pattern makes it feel more like the AttributeElementContainer is tied to each element rather than being truly freestanding.

I am also curious whether the AttributeElementContainer is actually useful in a script context. Is there a scenario where you would intentionally work with it, or is it something that should simply be filtered out?

I am not trying to argue the behaviour is definitely a bug, I just want to understand the reasoning so I know when and why to avoid this combination.