I trigger a minor cursor bug in Gmail's composer all the time, and it's driving me nuts. Here's the bug:
- Reply to an email and type something.
- With the cursor at the end of the line, press the down arrow key to highlight the "..." quote chip.
- Press the left arrow key. The cursor appears back at the end of the line of text.
- Type a letter. Gmail inserts a newline and the letter appears on the next line.
I often use down+left as a shortcut to get to the end of the current line (since Gmail doesn't support Ctrl-E), so this happens to me all the time.