Faulty CustomItems in a Form only
display a single Alert with the text "Application error",
regardless of how many CustomItems are in the Form.
The standard navigation or arrow keys are used for CustomItem internal
and external focus traversal (between Form items). With TRAVERSE_HORIZONTAL and TRAVERSE_VERTICAL fields,
it is possible to add internal
traversal within the CustomItem. TRAVERSE_HORIZONTAL is
not supported on devices with only 2-way navigation.
S60 and Series 40 devices
also support KEY_PRESS, KEY_RELEASE,
and KEY_REPEAT interaction modes.
In general, the keys that are visible in Canvas to MIDP applications are also visible in CustomItem.
The two exceptions in this are the navigation keys, which are used for CustomItem internal
and external focus traversal, and a possible Selection key that is used for
activating the Item default Command.
These keys are not visible as low-level key events.
If the CustomItem supports internal focus traversal
then it is displayed in the Form with no additional border.
Otherwise it is displayed in the Form surrounded by implementation
specific border.
A Form containing a CustomItem object
is set current Displayable and CustomItem's
content remains blank although it should be visible.
This issue can be avoided if Display.getDisplay is
called at least once during the MIDlet's lifecycle before creating the CustomItem,
for example at the beginning of the MIDlet's constructor.
Note: CustomItem does not get low-level key events even
if there is no CommandListener. The command mapping is
the same as in any Form Item. However,
for backward compatibility to S60 releases prior to 3.2, it is possible to
enable low-level key event triggering from Selection key in CustomItem.
If this feature is enabled, no Commands are mapped to
Selection key. Instead the relevant low-level key event will be triggered.
To enable this feature the following attribute should be added to the JAD
or manifest file of the Java application with value true: Nokia-MIDlet-S60-Selection-Key-Compatibility.
For more information, see section JAD
and JAR manifest attributes.