Bug 281890 Encapsulate IRunAndTrack#notify parameters
IRunAndTrack has a notify method with four parameters. I have found a need for a fifth parameter (the old value on change/remove). The parameter should be encapsulated as an "event" argument so that we will be able to add more event parameters in the future without breaking compatibility
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/workbench/ui/internal/UISchedulerStrategy.java
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 * Copyright (c) 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
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package org.eclipse.e4.workbench.ui.internal;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.e4.core.services.context.IEclipseContext;
import org.eclipse.e4.core.services.context.spi.IRunAndTrack;
import org.eclipse.e4.core.services.context.spi.ISchedulerStrategy;
/**
 * A context scheduler strategy that uses the realm's async event queue for
 * processing updates.
 */
public class UISchedulerStrategy implements ISchedulerStrategy {
	private static final ISchedulerStrategy instance = new UISchedulerStrategy();
	/**