Add files
Click Add files or drag films and stills in from Finder. They land at the end of the list; drag them into the order you want. Nothing is scanned or watched, so a folder tidied behind the app's back cannot change what the room shows.
A file the wall cannot play, or would play silent, is flagged on its row before it ever reaches the projector. What it plays is the list.
Preview, then take
Clicking a row only previews it, on the laptop. The wall changes when you press Take, and at no other time. Everything else is safe to touch during a show: browsing, scrubbing the preview, switching playlist.
Each bus has its own playhead. Scrubbing the preview is invisible to the room, which is how you find a point in a film without the audience watching you look for it. Scrubbing the wall's strip moves the wall.
Fit
Contain letterboxes a clip whose shape does not match the projector, so the whole frame is seen. Cover fills the projection and crops the overflow. One projector, one way of filling it, so fit lives on the playlist rather than on each file.
Blackout
B or Escape cuts the wall to the slate and pauses whatever was playing. Pressing it again picks up on the same frame. A pause you made yourself survives a blackout.
The chosen display, volume and fit are the room's and are kept. The playlist is a document: save it, or it is gone with the window. Playlists are files says how.