Bug 17699 Java Editor: Local Histroy menu entries are enabled for read-only files
F1 - make file read-only - open it - observe: context menu contains Local History actions. Only compare makes sense for read-only files
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/compare/JavaHistoryAction.java
private TextBuffer fBuffer;
		private boolean fInEditor;
		
		JavaTextBufferNode(TextBuffer buffer, boolean inEditor) {
			fBuffer= buffer;
			fInEditor= inEditor;
		}
		
		public String getName() {
			if (fInEditor)
				return CompareMessages.getString("Editor_Buffer"); 
			return CompareMessages.getString("Workspace_File"); 
		}
		
		public String getType() {
			return "java";	
		}
		
		public Image getImage() {
			return null;
		}
		
		public InputStream getContents() {
			return new ByteArrayInputStream(fBuffer.getContent().getBytes());
		}