However, large screens cost a bunch of money. If the Auto PC manufacturer's cost for a 5" display is several hundred dollars, the cost to the consumer can then be over one thousand dollars. These displays are very expensive because of the temperature range they must operate in and endure without breaking. The car is an incredibly brutal environment. This is why you don't want to leave your nice laptop with the 14.1" display sitting in your ungaraged car during a Minnesota winter -- you'll be getting your display replaced. To help keep entry level prices semi-reasonable, it's still desirable to make an Auto PC with a small screen. So Microsoft did some work to help the application developer support large and small screens using a single application.

The forms manager, which is used for displaying information on the Auto PC, now supports scalable forms and constraint based layout. The standard controls that come with the Auto PC also scale themselves based on display size, and will take advantage of the extra screen real estate by showing more information than on the smaller screen, not just using larger fonts. The constraint-based layout in the forms manager allows the developer to position his or her controls relative to areas of the screen versus simple X/Y coordinates using control positions such as Lower Left, Center Top, Left to Right of Control, and fractional locations based on the size of the form (like 20 percent down from top of form).

The region manager API
The large display in Auto PC 2.0 is a natural surface for showing a digital dashboard. However, Auto PC 1.0 would only allow one application at a time to control the display surface. Since a digital dashboard typically aggregates together information from a multitude of sources for presentation to the user, more than one application needs access to the screen. As I mentioned earlier, you'd typically want your digital dashboard available regardless of the primary task you're performing with the Auto PC. Because the Auto PC is a multimedia, information, entertainment, and communication device, often times there's no one primary task. From a usability standpoint, it's very desirable to have the information for each of the applications being used to appear in exactly the same place on the display all the time. This prevents the need for the driver to search the screen for the information they're looking for, which would be distracting. Imagine for a moment that the speedometer on your car moved to a different location based on the last switch you turned or pressed in your car. You get the picture.

The region manager allows an Auto PC OEM to define one or more "regions" of the screen and associate applications with those regions, as shown in Figure A. Each of the regions that the OEM defines is called an "OEM area". There's also a "default region" that the primary application appears in. The default region has a minimum size of 256x64 pixels, but can be as large as the whole display and is defined by the OEM. Regions may not overlap, be larger than the primary display surface, or have an irregular shape for the default region.