By Graham K. Rogers

There have a number of major changes to System Preferences in OS X 10.8, Mountain Lion. Some preferences have seen minor alterations, although there have been many changes under the surface. The panel for Displays has similar functions to those available before, but there have been several revisions to this section, both obvious and subtle. A change may also be seen in the main System preferences panel with a new icon.

The Displays panel controls the way the monitor shows its content. It is normally in two sections: Display and Color. For a computer with an inbuilt display, like the MacBook Pro or the iMac, the information will be for the machine's own monitor. This will differ for computers that use an external device (Mac Pro, Mac mini). An additional panel -- Arrangement -- will appear when an extra external display is connected to a Mac.

Display

In previous versions of OS X a box to the left -- dominating the pane -- would show a list of resolutions that were available for the specific computer. That box is not immediately visible now. Instead there are two Resolution options shown on the right: Best for built-in display and Scaled.

The first of these is for the many users who will want to leave well alone and will be content with the setup as provided. However, the world is not perfect and it may be necessary to change resolutions (this is occasionally a problem when I attach the Mac to an external projector, for example). Selecting "Scaled" reveals a box with 7 options, from 800 x 600 up to the optimal 1440 x 900 (on my MacBook Pro). These resolutions cannot be edited, nor can we add any others.

Below the Resolution options is a slider for adjustment of brightness with a checkbox marked, "Automatically adjust brightness" just below. It is still possible to use the slider when the box is checked. When the Function keys (F1 and F2) are used, the slider also moves.

At the bottom of this and all Displays panels, is a checkbox marked "Show mirroring options in the menu bar when available". This differs from before when a convenient Displays icon had been available at all times. By holding down the Command + Option keys, a button appears, marked "Detect Displays" which may be useful when attaching other monitors.

Color

There is a warning here: if you are not sure, don't touch.

In the main box any profiles created are shown. Highlighting any profile will change the display to those specific settings. To the right are three buttons: Open Profile, Delete Profile, and Calibrate.

• Open Profile displays a panel with technical information concerning the specific profile selected in .ICC file format (Color profile format standardized by the International Color Consortium).

• Delete Profile is not available for the default Color LCD settings on my MacBook Pro. The other profiles I had created, could be deleted.

• Calibrate brings up a utility named Display Calibration Assistant. This has a normal mode and "Expert mode" accessed by checking a box. The utility walks users through the process of calibration (should this be needed) and creates a new profile, so the computer can be returned to the original state if required.

Arrangement

This feature is especially useful when editing photographs or movies. It is also used with presentations: with Keynote the user's screen can have a Presenter Display which shows current and next slides, along with elapsed times and presenter notes. This is also available in PowerPoint for Macs.

When two (or more) displays are used, a second panel appears with controls for the extra output that are similar to the main panel. Instead of a Mac there is a generic display icon similar to the one in the main System Preferences panel. In addition, a button appears at the bottom right of both panels, marked Gather Windows.

This works in whichever window the panel is when the button is pressed, so if it is in a window on an external display (mirrored or not), pressing the Gather Windows button will move both panels to that external window. In use, the second panel moves to the external source when adjustments are made but may be hidden on that second display, so this feature is useful

By clicking on the white Finder bar at the top of the blue Window shown in the preferences display it can be dragged to another of the windows shown. With this, the window on the external display may become the main (Finder) window and the computer is then controlled from there.

On the external display panel on my computer, I also have a Rotation button. I added this some time back using a Terminal command in the main panel, but it is now only shown when an external monitor is attached. With this, I am able to turn the display through 90, 180 and 270 degree options which may be useful when certain displays are used or some images need to be shown at different angles.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs.