I’m using Lion with a Magic Mouse. Sometimes when I’m navigating windows in Safari with the mouse, the page zooms in. I have never been able to work out what I was doing to make it zoom or how to zoom out. The only way I’ve found to go back to the original zoom is to close the window and then reopen it. Can you enlighten me?
Joe Forbes

See also: How to control your Mac with mid-air hand gestures

You are undoubtedly triggering one of Lion’s gestures. By default, when you use a Magic Mouse, if you double-tap with a single finger, you’ll zoom in on a Safari page element. To zoom out, simply double-tap again with that single finger. This is the Smart Zoom gesture.

This, and the fact that the Mighty Mouse can be sensitive to unintended gestures, is one reason we find it a less than ideal input device under Lion. Because it has no physical buttons that register an intended tap or touch, it’s possible to accidentally trigger gestures, as you found out. Thankfully, you have some options.

First, familiarise yourself with Lion’s gestures. You can do this within the Mouse system preference (or within the Trackpad system preference if you’re using that device). Simply hover your cursor over a gesture, and you’ll see a helpful video that demonstrates how to trigger that gesture and just what it does. Knowing what a particular tap, click, or swipe will do can help you avoid accidentally triggering unintended gestures.

Second, turn off any gestures that get in your way. If you can’t avoid zooming in on page elements when working in Safari, switch off Smart Zoom. If you find yourself accidentally moving between pages, turn off the two-finger side-to-side swipe gesture that initiates this action. Although gestures are one of Lion’s main features, if you find them distracting, there’s no shame in switching them off.