Image import progress and cancel

When adding a rather large raw image, I ran into some issues.
a) Importing blocks the entire UI and has no progress indication - Especially since it can take significant time, a progress indicator would be great.
b) When realizing that data was being copied and that the available space would not suffice, I could not cancel the process. This lead to ultimately killing the app with the side effect of not knowing if any temp stuff is not getting cleaned up.

c) UI does not indicate that the raw image would be copied. It's not necessarily the most important part, but some indication that copying will happen would have made it easier to understand. This is explained in the docs but there's a good chance people find that only after a similar experience.