Bug 29163 SafeRunnable needs to be accessible in JFace
We need to be able to access the SafeRunnable in JFace in order that some error protection can be added to preferences and properties dialogs.
bundles/org.eclipse.ui.workbench/extensions/org/eclipse/jface/operation/ModalContext.java
/**
	 * Indicated whether ModalContext is in debug mode;
	 * <code>false</code> by default.
	 */
	private static boolean debug = false;
	
	/**
	 * The number of nested modal runs, or 0 if not inside a modal run.
	 * This is global state.
	 */
	private static int modalLevel = 0;
	
	/**
	 * Indicates whether operations should be run in a separate thread.
	 * Defaults to true.
	 * For internal debugging use, set to false to run operations in the calling thread.
	 */
	private static boolean runInSeparateThread = true;
	/**
	 * Thread which runs the modal context.
	 */
	private static class ModalContextThread extends Thread {
		/**
		 * The operation to be run.
		 */