I don't understand how to change width of edit form in JqGrid. I found option 'width' but I don't know how to use it (there isn't example).
You probably know the method navGrid. It has parameters in the form
$("#list").jqGrid('navGrid','#pager',{parameters},
prmEdit, prmAdd, prmDel, prmSearch, prmView);
where the parameter prmEdit
can contain any options of editGridRow method inclusive the width option which you need. So if you need for example to have edit form with 500px width instead of default 300px you can use
$("#list").jqGrid('navGrid','#pager',{},{width:500});
To simplify you the implementation I modified an example from my another answer so that the edit dialog has 200px: see it live here.