* Fixes the position of the specified vertex
* @param cell the vertex to position
*/
protected void setVertexLocation(mxGraphAbstractHierarchyCell cell)
{
mxGraphHierarchyNode node = (mxGraphHierarchyNode) cell;
Object realCell = node.cell;
double positionX = node.x[0] - node.width / 2;
double positionY = node.y[0] - node.height / 2;
rankTopY[cell.minRank] = Math.min(rankTopY[cell.minRank], positionY);