is there a way to have a component in a glyph and only refer to its outline and not its sidebearings?
An example. Assume you use the period to create the elipsis. If you position the three dots in the elipsis and afterwards change the sidebearings of the period, the elipsis is going to be messed up (similarly if you move the parent component vertically).
Auto alignment can also be done with #exit and #entry anchors. Changing metrics of the period will influence the LSB and RSB of ellipsis (which makes sense, I think), but leave the space between the periods the same.
I still believe that if you find a way to have an option to include a component without any reference to its sidebearings it is going to be a great addition.
There needs to be a reference point. Now, that point is the glyph origin. That is mostly what you need (when building accented letters). Another option would be to use the bounding box of the outline in the base glyph. But that has its pitfalls, too. If you extend something to the left, the components move to the right. So we need something that is independent of the outline and the metrics. I’m thinking about adding an ‘origin’ anchor (suggestion for a better name are welcome).