Gmail blue bar issue

Typical, no sooner do I post the issue, than I work out what was causing it. It was the Google Calendar gadget from the Google Labs settings page. The badly formatted email was in line with the top of the gadget.

Answering my own question, it turned out the problem was during switching from rich formatting to plain text:

• if previously I used plain text, Gmail will break long lines properly
• if previously I used rich formatting, Gmail will quote Outlook style, and when I press 'plain text', Gmail will reformat the reply to plain text, but long lines are not broken

So the solution if previously I chose rich formatting is:

• reply
• click 'plain text'
• discard
• reply again