@Override
 public View getGroupView(
     final int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
   if (convertView == null) {
     LayoutInflater inflater =
         (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
     convertView = inflater.inflate(R.layout.group, null);
   }
   ImageButton btn = (ImageButton) convertView.findViewById(R.id.discardBtn);
   btn.setFocusable(false);
   btn.setOnClickListener(
       new View.OnClickListener() {
         @Override
         public void onClick(View v) {
           Log.d(TAG, "group with time " + titles.get(groupPosition) + " clicked!");
         }
       });
   CheckedTextView tw = (CheckedTextView) convertView.findViewById(R.id.checkedTW);
   Title title = titles.get(groupPosition);
   tw.setText(title.getDate());
   tw.setChecked(isExpanded);
   TextView coordsView = (TextView) convertView.findViewById(R.id.coordsView);
   coordsView.setText(
       "Floor: " + title.getZ() + ". Position [" + title.getX() + ", " + title.getY() + "]");
   return convertView;
 }