New messages get highlighted as the currently selected message (which is not correct)

[runboxdave]

Describe the bug When a new message arrives it gets highlighted as the currently selected message even though a previous message is shown in the preview.

To Reproduce Steps to reproduce the behavior:

1. Highlight a message and check the preview is for the correct message.
2. Wait for a new message to arrive.
3. New message will be highlighted.

Expected behavior New messages should not be highlighted as the currently selected message as this causes a mismatch between the highlighted message and any open preview.

It's preferable that the expected behaviour above is implemented because the alternative would be to update the preview and this could be annoying if reading that message at the time a new one arrives.