private int getChildSize(final PanelDefinition panel) {
   int childSize = 0;
   final PanelDefinition eastPanel = panel.getChild(Position.EAST);
   final PanelDefinition westPanel = panel.getChild(Position.WEST);
   if (eastPanel != null) {
     childSize = childSize + assertSize(eastPanel.getWidth()) + getChildSize(eastPanel);
   }
   if (westPanel != null) {
     childSize = childSize + assertSize(westPanel.getWidth()) + getChildSize(westPanel);
   }
   return childSize;
 }