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User Interface Guidelines

When designing your application, keep in mind the following differences between a handheld device and desktop computer:

Display & Form layout.

Most of the Palm OS^® handhelds have a monochrome or color screen of 160x160 pixels resolution or 320x320. Therefore, keep it simple and avoid overloading the interface with unnecessary controls:

• Do not leave a margin around your interface: the nonactive surface of the LCD will form one.
• Avoid the use of decorative images.
• Avoid the practice of making all your buttons the same width. The ideal size of a button is that of the text it contains plus two extra pixels at the edge.
• Most of the PalmOS^® applications use bold only for labels. Any element not displayed in bold is editable or reactive.
• Do not waste the space available in the title bar: you can display useful information there such as the current date (in an agenda application foir example) or the current status of your application (edit, new record).

Data Entry

Data entry being carried out with the stylus, avoid as far as possible text entry fields: use drop-down lists wherever possible or date/hour selectors. In addition, even if it is programmatically possible to obtain control behavior different from those for which they were designed, avoid this practice.

The Grid control allow to perform different kind of behavior. It can display Field, Checkbox, Popup and more.

Any form having a text entry control must have in the bottom right a Graffiti control indicating the status of the writing recognition zone.

Navigation

Some common sense remarks:

• Whereas the user of desktop PC launches an application to use it for several minutes at a time, the tasks carried out on a handheld device are short and the user switches frequently from one application to another. Thus, your application must launch itself quickly and to be able to restore its state.
• Remember that the user may be standing in public transport, on the telephone, in the street, a vehicle, etc.
• Make key functions available from simple a click of stylus: reserve the menus for the commands more rarely used.
• If possible, add command strokes for each menus command.
• Add a help message to the modal dialog boxes (Help property). It will be accessible by clicking on the help icon from in top right.
• Make sure that a dialog box never opens another dialog box.
• If a dialog box only contains one text entry field, have the cursor ready and visible by setting the form Focus property to this control.

The user expects that your application will behave like the other Palm OS^® programs, i.e. it reacts to all the systems events, information it contains is accessible through a global search, that it allows the organization of data into categories, that it receives alarms, that it displays numbers and dates according to system preferences etc... Observe the applications provided with Palm OS^® such as To Do List or Address Book, and like them:

• Present on the first screen an overview of available information in the form of list or of grid.
• Clicking on this information should display details and offer editing possibilities.
• Present in top right a drop-down list of the categories.
• Gather all the details related to a record in a modal dialog box.