// Build list of data columns, and hide non-visible edge columns in the EdgeCell set
// to ensure that colspans are appropriately recomputed
List dataColumns = ListUtil.list();
for (int i=0, count=displayColumns.size(); i < count; i++) {
Column c = (Column)displayColumns.get(i);
c.prepare(_dataTable);
if (c.isValueColumn(_dataTable)) {
dataColumns.add(c);
}
else if (c instanceof PivotEdgeColumn) {
((PivotEdgeColumn)c).edgeCell().setHidden(true);