Key Repeat Rate, Delay Until Repeat. In Mavericks, holding down letter and number keys no longer makes them repeat, much to the disappointment of people who like to type, for example, “AAAAAARRRRRRGGGGHHH!” Instead, holding down a key produces a palette of alternative accented versions of that letter, like é, è, ê, ë, and so on.

Only the punctuation keys still repeat, so at least you can still type ****** or ????? or !!!!!!!.

There are sneaky ways to make your regular keys repeat, as they did in days gone by; see Dictation. In the meantime, these two sliders govern the repeating behavior of the punctuation keys. On the right: a slider that determines how long you must hold down a key before it starts repeating (to prevent triggering repetitions accidentally). On the left: a slider that governs how fast each key spits out characters once the spitting has begun.

Use all F1, F2, etc. keys as standard function keys. This option appears only on laptops and aluminum-keyboard Macs. It’s complicated, so read Desktop Exposé slowly.

Adjust keyboard brightness in low light. This setting appears only if your Mac’s keyboard does, in fact, light up when you’re working in the dark—a showy feature of many Mac laptops. You can specify that you want the internal lighting to shut off after a period of inactivity (to save power when you’ve wandered away, for example), or you can turn the lighting off altogether. (You can always adjust the keyboard brightness manually, of course, by tapping the and keys.)

Show Keyboard & Character Viewer in menu bar. You can read all about these special symbol-generating windows on Checkbox Options. Here’s the on/off switch for the menulet that makes them appear.

Set Up Bluetooth Keyboard. Yes, you’re absolutely right: This button lets you set up a Bluetooth (wireless) keyboard.

Modifier Keys. This button lets you turn off, or remap, the functions of the Option, Caps Lock, Control, and ⌘ keys. It’s for Unix programmers whose pinkies can’t adjust to the Mac’s modifier-key layout; for anyone using a PC keyboard on which the Option (Alt) and (Windows) keys are in the “wrong” positions relative to each other; and for anyone who keeps hitting Caps Lock by accident during everyday typing.