As i am trying to learn Affinity Photo, I'm running into situations where it feels the app has frozen, but i am waiting for Photo to finish some processing. There needs to be an indicator that something is happening. I see that some of the tools and processes cover the screen with a progress bar. This is a bit heavy handed, but it needs to be present for every situation where the user is forced to wait. I recommend a less intrusive version of it, as well (covering the whole screen is too much).