Anyone who has chatted in a team game has experienced the frustration of trying to enter a public comment but have it post as a team comment. You can't even copy and paste the comment to the chat window and send it again because it won't accept identical posts. You have to type something different. This problem isn't a serious problem but it is a nuisance that occurs very frequently to many players.
I discovered today why it is that I, and so many others, do this so often. When I am typing in the chat window, another window opens up suggesting chat options and the like, and this new window opens over the check box for "teammate" chat. In fact, while I type, I often wonder if I have the box checked or not and the box is often hidden. I realize that not every user will have these additional windows opening up and covering the check box and that it depends on personal settings, but a very large number of us do share these settings.
Solution: Move the check box to the top of the chat window instead of it's present location, right below the chat entry window.
Benefit: The obvious benefit is a more convenient and more enjoyable chat experience, thus a better game experience.