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Palm OS Programming, 2nd Edition by Neil Rhodes, Julie McKeehan

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Form Characteristics

There are three types of forms commonly found in your application:

  • Alerts

  • Dialog boxes

  • Modeless forms

You should think of a form as a container for the visual elements (form objects) of your application. Unlike desktop operating systems in which overlapping windows can each be active and brought to the front by tapping, on the Palm OS, there is only one active form (the frontmost one). Any other forms are inactive; their objects don’t respond to stylus taps.

Within the Palm OS there are two types of forms: modal and modeless. Table 8-1 shows you the characteristics of both types.

Table 8-1. Characteristics of modal and modeless forms

Modeless

Modal

Fills the screen (160 x 160 pixels)

Horizontally fills the screen

Justified to the bottom of the screen

No frame

2-pixel frame

Title left-justified

Title centered

Each form has these characteristics:

Form attributes

These are attributes defined for the form. They control the form’s behavior and appearance. They are normally specified in the resource, although some of the attributes can be changed at runtime.

Title

This null-terminated string is the title of the form. For modal forms, the title is centered; for modeless ones, the title is at the top-left of the form. Modeless forms need not have titles, though they should so that the user knows which application is running.

Modal

This bit specifies whether the forms should be drawn as modal forms (with framing and the title centered). The frame of a modal form ...

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