rogerano, excellent refinement on point two. No questions on rounding.
I wasn't thinking drag and drop planet improvements, I guess I didn't explain myself well. Sometimes, I'll want to place three factories. I'll doubleclick to place a factory, then doubleclick two more times to place two more factories. The problem I run into is when the list has scrolled, it scrolls back to the top as soon as I place the first item, so I wind up placing the wrong item for the other two things. Annoying enough when I notice, but I don't always notice.
That's why I suggested trade embargos. It's already in game as a player option, so it probably wouldn't take too much work to make it work for the AIs as well. The only hard part is making sure that the AI can effectively use them, or at least not be abused by them.