Add selection sync to group-checkbox-select example. TODO: allow selection and deselection while hidden

Author: 6pac

examples/example-grouping-checkbox-row-select.html

@@ -350,11 +350,13 @@ <h2>View Source:</h2>
   dataView.onRowCountChanged.subscribe(function (e, args) {
     grid.updateRowCount();
     grid.render();
+    dataView.syncGridSelection(grid, true, true);
   });
 
   dataView.onRowsChanged.subscribe(function (e, args) {
     grid.invalidateRows(args.rows);
     grid.render();
+    dataView.syncGridSelection(grid, true, true);
   });