I often only want the outer lines of a given 2D object that I've imported., e.g. this set of roof line work where I only want the outer roofline.
I realise a lot of these lines cross into the inner space (and I'll need to trim them) but just getting the outer ones in a selection would remove a tedious small repeted action.
I want to do this with drawn elements, and items like surveyor's TINS, and also the jumble of objects that results from exploding .pdfs (where there is normally only a single layer in the drawing).