If a message thread is open with person A and a new message comes in from person B, thread B will overlay A for your quick response to B, then flip back to A so quick you may not notice you're back in thread A. Typing a second response to B often goes to A unnoticed due to this switch back. Suggesting a better way to show the transition back to thread A so users are aware, without having to customize each thread's color theme to visually see the difference.