User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 Build Identifier: Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv:1.9.1.5) Gecko/20091121 Thunderbird/3.0 When pasting text into the Compose pane that was copied from an html source such as a Web page in Firefox, the cursor jumps to the Home position (1,1) of the compose pane. This does not happen when pasting plain text. Reproducible: Always Steps to Reproduce: 1. Type a few words into a new message 2. Copy something in a browser page and paste on the bottom of the message you started 3. The cursor jumps to 1,1 Actual Results: Cursor moves to Home position Expected Results: Cursor position after new insertion Just a note that I noticed another bug #261392 with html paste (can't undo). Also, I don't know that this is Mac-specific, someone kindly test on other OS's.