Screen Shrink is a utility to assist PDA, mobile phone and iPhone developers see how their applications look on displays of various sizes and resolutions. Screen Shrink is shareware ($15).

Magnification of displays are set using two magnification sliders in the Control Panel; the Display Windows can be set for resolutions between 72 and 300 dots per inch. When you launch Screen Shrink you see a small Control Panel and three Display Windows in front of a Background Window. There are two modes of operation, normal and locked.

Above you see three Display Windows (you can choose to see one, two or three), each at a different DPI resolution (72, 200, 300), and the small Control Panel. Magnification is set for 100%. Display is in the locked mode and crosshairs are not selected.

In normal mode, you see a dynamic display of the desktop around your mouse in each Display Windows. In locked mode, you indicate where you want the Display Windows to watch and you are then free to use your mouse normally.

To enter the locked mode, put your mouse over the point you want to watch and press Command-L keys. You will see a small red "locked" light to the right of Shrink/Expand in the Control Panel.

To revert to the normal mode, press Command-Shift-L keys. The red "locked" light will go out.

From the Control Panel, you can Show or Hide the Display Windows, turn crosshairs on/off, and choose the desired magnification using Coarse and Fine sliders. Magnification (less than 10% to 100%) change is seen immediately in the Display Windows. Adjust the settings, drag the Control Panel out of the way on the desktop, and click on the small triangle to make the Control Window as small as possible. To expand the Control Window, click again on the triangle.

There is a menu pick to choose one, two or three Display Windows. Drag the Display Windows where you wish and adjust the window sizes by dragging the bottom right corners.

If you close the Background Window, you can bring it back by pressing Command-B. You can resize and move the Background Window and then drag the Display Windows on top of the Background Window. The initial color of the Background Window is gray. Control-click on the Background Window (twice, once to get focus and once to bring up a contextual menu) to select the desired Background Window color (gray, white or black).

Control-click on a Display Window (twice, once to get focus and once to bring up a contextual menu) to use a slider to set the display Dots per Inch, the Display Window's width and height at 72 DPI resolution, and select the refresh rate (fast, medium or slow). Note: Selecting a DPI other than 72 adjusts the display window's size to compensate for the higher resolution. The refresh rate setting is shown on the Control Panel to the right of the "locked" light. "F" indicates fast; "M" indicates medium; "S" indicates slow.