got it:
grid.grouping.groupBy = ['productName'];
grid.grouping.enabled = true;
grid.grouping.expandMode = true;
grid.columns[2].visible = false;not sure if this is documented anywhere, but the chrome-console helped me to find this by reverse-engineering a working grid-group example.
using grid dynamically is incredibly powerful. i hope that smart-elements starts to provide examples of dynamic-grid. i believe that others would find it exceptionally useful.
