Unless there is some method I am missing, I find it a bit cumbersome to find out which of my planets are idle in one or the other of their production queues. I go to the "planet" list, scroll down until I see an empty line, then click on the planet to see if there is something that I could (or want to) work on ... and then I have to go back to the top of the list to start scanning again. An "idle planet" button would be very helpful.