we want to totally override the reconfigure behaviour here, since we're creating 2 sub-grids
function(store, columns) {
        var me = this,
            oldStore = me.store,
            lockedGrid = me.lockedGrid,
            normalGrid = me.normalGrid;

        Ext.suspendLayouts();
        if (columns) {
            lockedGrid.headerCt.removeAll();
            normalGrid.headerCt.removeAll();

            columns = me.processColumns(columns);

            // Flag to the locked column add listener to do nothing
            me.ignoreAddLockedColumn = true;
            lockedGrid.headerCt.add(columns.locked.items);
            me.ignoreAddLockedColumn = false;
            normalGrid.headerCt.add(columns.normal.items);

            // Ensure locked grid is set up correctly with correct width and bottom border,
            // and that both grids' visibility and scrollability status is correct
            me.syncLockedWidth();
        }

        if (store && store !== oldStore) {
            store = Ext.data.StoreManager.lookup(store);
            me.store = store;
            lockedGrid.bindStore(store);
            normalGrid.bindStore(store);
        } else {
            lockedGrid.getView().refresh();
            normalGrid.getView().refresh();
        }
        Ext.resumeLayouts(true);
    }