11.5. Defining a Widget Set

The client-side components, or in GWT terminology, widgets, must be made usable in the client-side GWT application by defining a widget set. A widget set is actually a GWT application and needs to be defined in the GWT module descriptor as the entry point of the client-side engine. A GWT module descriptor is an XML file with extension .gwt.xml.

If you are using the Eclipse IDE, the New Vaadin Widget wizard will automatically create the GWT module descriptor. See Section 11.2.1, “Creating a Widget” for detailed instructions.

The following example of ColorPickerWidgetSet.gwt.xml shows the GWT module descriptor of the Color Picker application. We also define the default stylesheet for the color picker widget, as described above in Section 11.3.3, “Styling GWT Widgets”.

<module>
	<!-- Inherit the default widget set -->
	<inherits name="com.vaadin.terminal.gwt.DefaultWidgetSet" />
	
	<!-- The default theme of this widget set -->	
	<stylesheet src="colorpicker/styles.css"/>
</module>

Compiling widget sets takes considerable time. You can reduce the compilation time significantly by compiling the widget sets only for your browser, which is useful during development. You can do this by setting the user.agent property in the .gwt.xml GWT module descriptor.

<set-property name="user.agent" value="gecko1_8"/>

The value attribute should match your browser. The browsers supported by GWT depend on the GWT version, below is a list of browser identifiers supported by GWT 2.0.

For more information about the GWT Module XML Format, please see Google Web Toolkit Developer Guide.