Let's be fair here. These are chat bubbles. They're not buttons or text boxes. There's no inconsistency in behavior between different versions in different UIs. They're just a pretty way of displaying a chat conversation. It's generally pretty easy to recognize when you're in a chat, and bubble shapes are distinctive. You could even use the tried-and-true text chat approach. This is reasonable as a way to avoid phishing-type scams where you fake IM or SMS to steal information.