We have a problem with smart rendering.
If we turn it on the filter of some columns does not work correctly:
Heres an example without smart rendering and with filters working correctly:
with smart rendering on and filters messed up:
Can you help us?
The problem is with usage of NULL in the value of your cell.
Please, try to replace null with the empty value ("") as a workaround.
That problem will be fixed in the future version of the dhtmlxGrid.