Palm webOS

Dialogs

You can use a Dialog widget to create a modal view for almost any purpose. A custom dialog is a conventional dialog, but it requires a widget assistant and an HTML template file. The Dialog widget is dynamically instantiated within a scene assistant, so there is a bit of overhead in using it both for you as a developer and at runtime. For errors, you should use the Error dialog. For presenting some simple options, use an Alert dialog. The simple built-in dialogs will be presented first, followed by a discussion of how to build custom dialogs with showDialog.

Error Dialog

You can post error messages in a modal dialog box with a fixed title of “Error,” a customizable message, and a confirmation button. The Error dialog must be used only with errors, since you can’t change the title; an example is shown in Figure 4-1.

You can post an Error dialog box with a single call:

Mojo.Controller.errorDialog(“Invalid Feed”, this.controller.window);

Figure 4-1. An Error dialog box

Logging Methods

Mojo includes logging methods to give you an efficient way to generate console output without degrading the performance of your application or the system. There are three log levels:

Mojo.Log.info();     // Mojo.Log.LOG_LEVEL_INFO = 20
Mojo.Log.warn();     // Mojo.Log.LOG_LEVEL_WARNING = 10
Mojo.Log.error();    // Mojo.Log.LOG_LEVEL_ERROR = 0

Only messages at or below the current logging level are generated. The current ...