I've run into a problem with grids that have expand rows. This can be reproduced using the Master Detail grid example. Just go to that page and run the following:
$('#dg').datagrid('appendRow', {"itemid":"EST-99","productid":"FI-SW-01","listprice":"16.50","unitcost":"10.00","status":"P","attr1":"Large"})
Now try to scroll to the bottom and expand EST-26. You'll get a - icon, but no expansion data. If you click the - icon, it will change to a + but it will "eat" EST-99, the row below it. Clicking the + icon will then make EST-99 re-appear.
There are several other ways to show it being glitchy, but it's likely that one fix will fix them all so I'll leave it at this.