title: onLongPress PaginatedDataTable DataRow
body: <p>What is the best way to have an entire row trigger a callback when Long Pressing anywhere in it. Im using a <code>PaginatedDataTable</code>, which contains <code>DataRow</code>'s of <code>DataCell</code>'s.</p>
  
  <p>The only way I found was by adding a <code>TableRowInkWell</code> or <code>GestureDetector</code> inside each <code>DataCell</code> but this doesn't work right, you need to actually long press on the text inside any of the cells to work.</p>
  
  <p>Ive also tried adding padding to enlarge the selection area but that messed up the datatable itself.</p>
  
  <pre><code>      dataCells.add(DataCell(
          TableRowInkWell(
            onLongPress: () {
              // do something
            },
            onTap: () {
              // do something
            },
            child: ConstrainedBox(
              constraints: BoxConstraints(maxWidth: 150),
              child: Text(
                content,
                overflow: TextOverflow.fade,
                maxLines: 1,
                softWrap: false,
              ),
            ),
          ),
        ));
  </code></pre>
  
  <p>Also <code>DataRow.byIndex</code> doesn't have any callbacks other than <code>onSelectChanged</code> which works for <code>onTap</code>.</p>
  
  <pre><code>   return DataRow.byIndex(
          onSelectChanged: (bool value) {
            // do something
          },
          index: index,
          cells: dataCells
      );
  </code></pre>