code: public void inputChanged(Viewer viewer, Object oldInput, Object newInput)
  	{
  		super.inputChanged(viewer, oldInput, newInput);
  		this.viewer = viewer;
  	}
docs: /*
  (non-Javadoc)
  @see org.eclipse.ui.model.WorkbenchContentProvider#inputChanged(org.eclipse.jface.viewers.Viewer,
  java.lang.Object, java.lang.Object)