@Override
 public void disconnect(IDocument document) {
   if (document instanceof DisassemblyDocument) {
     final IBreakpointManager bpMgr = DebugPlugin.getDefault().getBreakpointManager();
     bpMgr.removeBreakpointListener(this);
     document.removeDocumentListener(this);
     fCatchup = null;
   }
   super.disconnect(document);
 }