People interested in shaping features for Gmail, Google’s free mail service in beta for about the last half-century, can now test their latest creations in a safe new environment. The company Friday launched Gmail Labs, a type of sandbox that people can use to test and provide feedback on Gmail features under development or consideration.

If you’re a Gmail user with Firefox 2 or Internet Explorer 7 and interested in trying it out, log into Gmail and go to Settings>Labs. You’ll see a list of available features that you can individually enable. You’re in the sandbox with all the new features from then on.

Among the new features is “Superstars,” which adds checks, exclamation points and colors beyond yellow for the stars next to messages. There's also pictures in chat, customizable keyboard mappings, and my favorite--mouse gestures-- which lets you easily navigate e-mail with right-click-drags left and right for next and previous messages and up to return to the inbox.

Before you begin, Google on its Gmail Labs about page offers these caveats:

• Features may break at any time
• Features may disappear temporarily or permanently
• Features may work so well that they graduate and become regular features

Feedback can be left at the Labs Google Group.

If things become unstable in the Lab, Google gives we brave souls a way to back out. Use this URL or simply put a “labs=0” at the end of your normal Gmail URL to disable all Labs features. If that doesn’t work, follow the directions on the Disable Labs page, which steps you through using Gmail>Labs settings. I found no need- everything I tried worked well, though some features were sluggish. But hey, it's beta.