When I first open Nitro on Mac, I’m able to navigate forward/backward in the thumbnail panel with the arrow keys. But if I hit Tab, a focus ring appears around the image preview area, and from that point on I’m no longer able to navigate with the arrow keys, and I can’t figure out how to return to the original state without quitting and restarting the app.
Thanks for reporting that. It’s a bug and I’ll make a note to fix it.
One way to get out of this is to hit the escape key. It will take you back to the grid and the keyboard should work again.