Say I've got a few battlecruisers in a division. My fleet is in a good position relative to the enemy, but there's a couple cruisers retreating in a different direction after they've taken some damage. I want to detach 1 of my ships to go and chase them down and finish them off. So I select the rearmost ship of my formation, click the "detach" option.
What I'd expect is that the solo ship would remain selected, so when I right click, it'll be the 1 ship being sent to chase down the retreating ships.
What actually happens is that the initial division the ship had been part of remains selected, and when I click to send my 1 ship to chase down the stragglers... the whole division heads that way except the 1 ship I detached.
Don't know about other people, but I'd prefer it if the lone ship was what remained selected so I can immediately give it orders.