Bug 287139 [CommonNavigator] Add core expression to determine initial activation for NCE
Build ID: 20090619-0625 Steps To Reproduce: Currently, the definition of the Navigator Content Extension via plugin.xml allows to specify the boolean attribute allowByDefault which controls if the contributed content is active by default. It makes sence to change the type of the attribute from boolean to core expression, which will allow to evaluate the default context and show content depending on it. This will ease the control of content and enhance the declarative configuration of CNF and NCEs. More information:
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/INavigatorContentDescriptor.java
* @noimplement This interface is not intended to be implemented by clients.
 * @noextend This interface is not intended to be extended by clients.
 * @since 3.2
 * 
 */
public interface INavigatorContentDescriptor {
	/**
	 * Returns the navigator content extension id
	 * 
	 * @return the navigator content extension id
	 */
	String getId();
	/**
	 * Returns the name of this navigator extension
	 * 
	 * @return the name of this navigator extension
	 */
	String getName();
	/**
	 * Returns the priority of the navigator content extension.
	 * 
	 * @return the priority of the navigator content extension. Returns {@link Priority#NORMAL}
	 *         if no priority was specified.
	 */
	int getPriority();
	
	/**
	 * Returns the extension that this extension must appear before.
	 * 
	 * @return The value specified by the <i>appearsBefore</i> attribute of the