Bug 17423 Revert apears twice in the popup menu.
Build F1. 1) Open a java editor. 2) Popup the menu. There is only one Revert option disable as it should be. 3) Make the editor dirty. 4) Popup the menu. There are two Revert option in the menu. One after UNDO and other before FORMAT.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
*/
	protected void handlePreferenceStoreChanged(PropertyChangeEvent event) {
		
		try {
			
			AdaptedSourceViewer asv= (AdaptedSourceViewer) getSourceViewer();
			if (asv != null) {
					
				String p= event.getProperty();		
				if (CODE_FORMATTER_TAB_SIZE.equals(p) || CODE_FORMATTER_TAB_CHAR.equals(p)) {
				    SourceViewerConfiguration configuration= getSourceViewerConfiguration();
					String[] types= configuration.getConfiguredContentTypes(asv);					
					for (int i= 0; i < types.length; i++)
					    asv.setIndentPrefixes(configuration.getIndentPrefixes(asv, types[i]), types[i]);
					    
					if (fTabConverter != null)
						fTabConverter.setNumberOfSpacesPerTab(getPreferenceStore().getInt(CODE_FORMATTER_TAB_SIZE));
				}
				
				if (SPACES_FOR_TABS.equals(p)) {
					if (isTabConversionEnabled())
						startTabConversion();
					else
						stopTabConversion();
					return;
				}
				
				if (MATCHING_BRACKETS.equals(p)) {
					if (isBracketHighlightingEnabled())
						startBracketHighlighting();