I can't figure out how Godot makes certain ui widgets, such as the editable boxes for Vector values, or curve editing boxes (like the one in the gif below). In fact I can't even figure out how Godot's inspector fields have a little down arrow next to them, since all the available buttons that have arrows (OptionButton and SpinBox) have two arrows and not one.
I'd like understand what pieces go into making this, for example: (WorldEnvironment's fog)
EDIT: On afterthought, the down arrow thing may be a property inherent to the ItemList's items (I suppose that's what's used for the inspector -- either that or a Tree). If that's the case, do the widgets in question have anything to do with that too, or are they built in some other way?
