Palm OS Programming, 2nd Edition

Alerts

An alert is a very constrained modal dialog box (see Figure 8-3). It is a modal dialog box with an icon, a message, and one or more buttons at the bottom that dismiss the dialog box.

Figure 8-3. An alert showing an information icon, a message, and a button

As we discussed in Chapter 3, there are four different types of alerts (notification, warning, question, and error). The user can distinguish the alert type from the icon shown.

UI guidelines recommend that modal dialog boxes have an Info button at the top-right that provides help for the dialog box. To do so, create a string resource with your help text and specify the string resource ID as the help ID in the alert resource.

Customizing an Alert

You can customize the message in an alert. You do this with runtime parameters that allow you to create as many as three textual substitutions in the message. In the resource, you specify a placeholder for the runtime text with ^1, ^2, or ^3. Instead of calling FrmAlert, you call FrmCustomAlert . The first string replaces any occurrence of ^1, the second replaces any occurrence of ^2, and the third replaces occurrences of ^3.

When you call FrmCustomAlert, you can pass NULL as the text pointer only if there is no corresponding placeholder in the alert resource. If there is a corresponding placeholder, then passing NULL will cause a crash. Pass a string with one space in it (" "