First screen is great but I can see the vestige of an additional screen to the right. (I use myReach on a Mac running Safari.) Swiping is not an option and there are no directional arrows to switch screens.
If I grab the visible corner of the next window banner, I can pull it into view. This continues for several screens.
Dots to indicate number of screens? Down arrow in left sidebar to permit selections? Directional arrows? All possible and user-familiar solutions.
Ignore if this is already being addressed in the Mac native application under development. If you need more info or screen shots, just ask.