Bug 250133 [Contexts] ContextAction's leak when hiding actions sets
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/contexts/ContextManager.java
import java.util.Set;
import org.eclipse.core.commands.common.HandleObjectManager;
import org.eclipse.core.commands.util.Tracing;
import org.eclipse.core.internal.commands.util.Util;
/**
 * <p>
 * A context manager tracks the sets of defined and enabled contexts within the
 * application. The manager sends notification events to listeners when these
 * sets change. It is also possible to retrieve any given context with its
 * identifier.
 * </p>
 * <p>
 * This class is not intended to be extended by clients.
 * </p>
 * 
 * @since 3.1
 */
public final class ContextManager extends HandleObjectManager implements
		IContextListener {
	
	private static final String DEFER_EVENTS = "org.eclipse.ui.internal.contexts.deferEvents"; 
	private static final String SEND_EVENTS = "org.eclipse.ui.internal.contexts.sendEvents"; 
	/**
	 * This flag can be set to <code>true</code> if the context manager should
	 * print information to <code>System.out</code> when certain boundary
	 * conditions occur.
	 */
	public static boolean DEBUG = false;
	/**
	 * The set of active context identifiers. This value may be empty, but it is