TL;DR
It would be good if the blueprint dialog would allow zooming and scrolling so details on large blueprint are visible.What ?
I suggest that zooming and scrolling are allowed in the blueprint dialog the same way they work in the game otherwise. The controls at the top of the blueprint should probably stay static and only the middle should zoom and scroll, similar to how the train view can be zoomed.Secondly I suggest adding a "zoom to fit" button as it might be hard to get back to the right zoom level to fit everything.