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/dialogs/ProgressMonitorDialog.java
open();
	try {
		runningRunnables++;
		
		
		progressMonitor.forked = fork;
		ModalContext.run(runnable, fork, getProgressMonitor(), getShell().getDisplay());
	} finally {	
		runningRunnables--;
		close();
	}
}
/**
 * Sets whether the progress dialog is cancelable or not.
 *
 * @param cancelable <code>true</code> if the end user can cancel
 *   this progress dialog, and <code>false</code> if it cannot be canceled
 */
public void setCancelable(boolean cancelable) {
	if (cancel == null)
		enableCancelButton = cancelable;
	else
		asyncSetOperationCancelButtonEnabled(cancelable);
}
/**
 * Helper to enable/disable Cancel button for this dialog.
 *
 * @param b <code>true</code> to enable the cancel button,
 *   and <code>false</code> to disable it
 */