Why the F hasn't this been implemented yet?
More detail:
BOB makes pop-ups warning you that you are ending attack phase and other things. I've heard that BOB has been integrated into the site, so it seems appropriate for me to ask about this here rather than in "tools and enhancements."
BOB/CC should have an option to warn you about attacking team mates, or your other selves in polymorphic games. Occasionally, you do it on purpose. But I probably mistakenly kill 1-2 "friendly" troops in half of my poly games/team games. Most often it happens when I think I've ended the attack phase, and I'm trying to fort to a neighboring territory. OOPS, 2 troops lost.