Hello,
This is not possible at all. Please look here:
http://www.trirand.com/jqgridwiki/doku.php?id=wiki:cell_editing
and read carfully.
What you try to do is: you edit a cell and before save it you call edit cell again.
editCell try to save a opened cell.
I suggest you to try with the 3 parameter set to false, but not sure if this will meet your requierments
Best Regards
Tony