Now you use debug or run with GHCi on a module (in contrast to run as application as you do on a cabal executable).
However, when you do that, you need to open up the command window and type in the start point of your debugging / run session.
Instead, you should be able to right click a word (like main) in your file and choose "debug this" or "run this in GHCi". It would be nice if it also worked on a selection for more complex expressions. In this way, we would rarely need to open up the command window and have it steal all that precious screen estate and hide our beautifully coloured code :)