When begin to edit a row, the 'onBeginEdit' event fires, in which you can get all the editors and attach all events on them. Please refer to the code below:
$('#dg').datagrid({
onBeginEdit: function(index,row){
var dg = $(this);
var ed1 = dg.datagrid('getEditor', {index:index,field:'productid'});
$(ed1.target).combobox({
onChange: function(value){
var ed2 = dg.datagrid('getEditor', {index:index,field:'listprice'});
// $(ed2.target).numberbox('disable'); // disable the editor
$(ed2.target).parent().hide(); // hide the editor
}
})
}
})