Please try to define a hidden column with multiple lines in the un-frozen columns.
<DataGrid :data="data" style="width:600px;height:250px">
<GridColumn field="itemid" title="Item ID" :frozen="true"></GridColumn>
<GridColumn field="name" title="Name" :frozen="true"></GridColumn>
<GridColumn field="name" title="" :cellCss="{visibility:'hidden'}"></GridColumn>
<GridColumn field="listprice" title="List Price" align="right" width="100"></GridColumn>
<GridColumn field="unitcost" title="Unit Cost" align="right" width="100"></GridColumn>
<GridColumn field="attr" title="Attribute" width="200"></GridColumn>
<GridColumn field="status" title="Status" width="100"></GridColumn>
</DataGrid>