If you use a Mac laptop with a trackpad, and spend quite a bit of time typing on it—perhaps you’re a writer for a Mac-related Web site or something—you’re probably well aware of what I consider to be one of the most-important settings in OS X: the “Ignore accidental trackpad input” checkbox on the Trackpad tab of the Keyboard & Mouse System Preferences panel. If you have your trackpad set up to click when tapped—which I do, as I find it much easier than tapping the button—and you do not enable the “ignore trackpad” option, you’ll find that your cursor (and hence, where your typing appears) jumps around your document any time your finger or palm accidentally taps your Mac’s trackpad.
With this feature enabled, I’ve found that the cursor usually remains where it’s supposed to be, even if I accidentally brush the trackpad. That’s usually, not always—sometimes I’ll accidentally tap-click after a typing pause for instance, not notice that I’ve done so, then resume typing. I usually only figure out what’s happened after I’ve merged two sentences together into one jumbled mess.
For those times when you’ll be typing a lot of text, and don’t want to worry about the trackpad at all, here are two solutions. The first solution is to keep a mouse with you, and plug it in when you’re ready to start an extended typing session. Then, in the Trackpad tab of the Keyboard & Mouse System Preferences panel, check the “Ignore trackpad when mouse is present” box, and start typing. As long as the mouse is plugged in, that’s the only way you’ll be able to move the mouse cursor. (Note that you can still move the cursor’s position within your text editor by using the arrow keys. You just can’t move the onscreen cursor via the trackpad.)
The second solution, and the one I prefer as it doesn’t require any extra hardware to lug around, relies on the Universal Access System Preferences panel. Open that panel, and switch to the Mouse & Trackpad tab. Check the box next to “Press the Option key five times to turn Mouse Keys on or off” to enable Option-key control over the Mouse Keys feature. Next, check the box next to “Ignore trackpad when Mouse Keys is on.” So what have you done? First, you set the system up so that pressing Option five times in a row will turn on Mouse Keys, which allows for full cursor control with the numeric keypad (which is embedded on the 789-UIO-JKL-M keys on a laptop). Next, you told the system to completely disable the trackpad when Mouse Keys is enabled. Using these two features together, you can put an end to all accidental cursor movement while typing.
Try it out by opening TextEdit, and then pressing Option five times in a row. Just like that, your trackpad will no longer work—you can click and drag on it at will, but the cursor won’t move an inch. Once you’ve finished transcribing War & Peace, press the Option key five times in a row again, and everything will be back to normal. There are two minor downsides to this technique. First, you won’t be able to use the embedded numeric keypad when in Mouse Keys mode, because those keys are reserved for moving the cursor around. As with the hardware solution, you can still use the arrow keys to move the cursor within your document in either normal or trackpad-off modes. Second, you may forget you’ve enabled this mode, and wonder why the trackpad on your laptop no longer works—so remember to try pressing the Option key five times in a row before resorting to a restart to fix the problem!