My problem is that i want to change the cell being editable or not in the edit form according to the content of the cell of the row that is selected to be edited. I used Oleg's example to this link: JQGrid: Dynamically set a cell to uneditable based on content to figure out how to change the cell from editable to not editable but i cannot get the cell value in order to compare it and decide if i want to change the edit option of the cell.
UPDATED CODE:
var Setcelluneditable=function(form) {
        return function (form) {
        var id = jQuery(list).getGridParam('selrow');
        var ret = jQuery(list).jqGrid('getRowData',id);
        alert("Arrived="+ret.Arrived);
        if (ret.Arrived=='Yes')
         {alert("hello"+id);
         jQuery(list).setCell(id,'Arrived','',{color:'red'}, editable:'0'});}
     }
     }; 
jQuery(list).jqGrid('navGrid',pager,{edit:true,add:true,del:true,search:false,view:true, reload:true},
                {
                    width:colwidth,
                    height:"auto",
                    reloadAfterSubmit:true,
                    closeAfterEdit: true,
                    recreateForm: true,
                    ajaxEditOptions: {cache: false},
            beforeInitData : Setcelluneditable("#editmod")
                },
                {
                            width:colwidth,
                            height:"auto",
                            reloadAfterSubmit:true,
                            closeAfterAdd: true,
                            recreateForm: true,
                            drag: false
                },
                {},
                {},
                {},
                {}); 
This does not seem to work because i change the Grid that has already been constructed.