Mac OS X 10.6: Using the Display pane of Displays preferences
You can use the Display pane of Displays preferences to specify how your display works. Not all options appear for all display models.
The amount of detail your display shows. Higher resolutions show more detail at a smaller size. Lower resolutions show less detail at a larger size.
How frequently your display is redrawn. If the rate is too low, your display may appear to flicker. If the rate is too high, the display may be black because it doesn’t support that rate. Check the documentation that came with your display for the best rate.
Scans for all the displays connected to your computer. Press this button if your computer doesn’t recognize a display you’ve just connected.
Moves all open Display preferences windows to the display showing this button. This button appears only if more than one display is connected to your computer.
Rotates the image shown on your display by the chosen amount. For example, if you have a widescreen display but would rather have a display that is taller than it is wide, you could rotate the display’s image 90 degrees and then physically rotate the display. Check the documentation that came with your display to make sure you can safely operate the display when it’s rotated.
Controls how light or dark your screen appears. Move the slider to the right to make the screen brighter and to the left to make it darker.
Show displays in menu bar
Displays an icon in the menu bar that lets you switch between your most frequently used resolutions.