It's not user error, or at least it's a combination of user technique and a possible design. It has to do with how the stock messaging app interacts with the Android system notification.
I recreated it this way. Open a text, but only from the notification bar. You will be taken directly to the conversation from that contact. Now, just hit the home button to get back to the home screen. Repeat this four times to let the open conversations build up. We'll call the earliest contact 1, the next 2, etc. for this example. Let's say you converse with these contacts over some time so that messages occur in this chronological order (opened from the notification menu if possible) : 1, you, 2, you, 3, you, 4, you, 1, 3, you, 3.
Now, you've read the message from contact 3, but quickly hit the back button because you need to send a message to contact 4. So you're back at the conversation list and select conversation 4. You compose and send your message and off you go. But, what can actually happen is that your message went to contact 1 because there is a bug that when you use the back button, it will take you to the conversation screen and when you select one, it will take you to the conversation with the last "unreplied" message received before the last conversation you didn't reply to, regardless of the one you actually select from the list. It's easy to miss that it took you to the wrong conversation as the on screen info can take a beat to update and it looks like you've select the right conversation. The kicker is the conversation list
does highlight the one you meant to select, but will take you to that other conversation. It's as if it's saying, "Hey, I know you want to go to that one, but you opened this message and jumped out of it without replying. Maybe you didn't see it."
It's pretty easy for people to not have seen this for a few reasons:
1. You open messages directly from the messaging app
2. You close out every conversation using the back button and don't let them build up on top of each other
3. Messages can come in such a sequence that the conditions are never correct
4. It has actually happened, only the last "unreplied" message was from the conversation you actually intended to enter
I was able to create reliably using my Google voice number to send myself text and watched it bounce around conversations seemingly randomly. It was only when I looked at the times of each message with no replies that I saw what it was doing actually had order to it.
About 30 minutes of experimentation to figure it out, but I had to know how this was happening as I could see it leading to an egregious error later.
Now to explain it to HTC...
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