New features of Take A Break are added in version 1.1 to serve the feedbacks from you. It is already submitted to the official Firefox extensions website. Please give it a try. The new features are -
You can enable sound for the short break. When it is enabled, the extension will keep beeping while the icon is flashing, and stop beeping when the short break ends. So you can know when to open your eyes if you close your eyes during the short break. It is also useful for those users who focus too much on the content to notice the changing of the icon on the status bar, or those who does not show the browser's status bar at all.
The Sound Option is off by default -- some people may find it annoying. You can enable it by going to the Options page.
A More Fancy Reminder Window
A more fancy reminder window pops up to remind you a rest. It gives some suggestions -- with graphics -- of what you could do during the long break. If you like a simple and clean dialog instead, you can use the next feature.
Write Your Own Reminder Text
You can let the Reminder Window show the text you choose. Go to the Options page, check "Use My Text in Reminder" and write down your own text. When you enable this option, you get a no-frills dialog.
Some people dislike the old set of icons. In this release, I use some new ones. I am not an artist, so don't expect too much. :)
A new online help for version 1.1 can be found here.
Thanks a lot to all of you for the reviews and suggestions. Your supports encourage me to keep on improving it.