Ok Bernard,i will use settimeout to resolve this problem.I thought the property 'IsInProgress' will be useful but it always same value.

It suddenly occurred to me shortly before i doing something with webGrid and it has the same problem that i did not know when to set value to webGrid in Client-Side,and i resolved the problem by using settimeout too.

Is the any possible to add some property or event to check WebControls are already loaded and ready to set value in the later version or some patch?I just feel it very strange that this product can't  finish such a simple request accurately.

Hi Bernard,

Thank for your reply first.The timeout i said comes from this issue.

In my case,i can confirm the value of WebCombo1 has been set.Here is my temporary solution:

ISGetObject("data_node").SetSelectedRowByValue(ctrl.datasource.db);
                if (ctrl.datasource.src != "") {
                    ISGetObject("data_table").LoadValue();
                    ISGetObject("data_table").ShowDropDown();
                    setTimeout(function () {
                        ISGetObject("data_table").SetSelectedRowByValue(ctrl.datasource.src);
                        if (ctrl.datasource.col != "") {
                            ISGetObject("data_col").LoadValue();
                            ISGetObject("data_col").ShowDropDown();
                            setTimeout(function () {
                                ISGetObject("data_col").SetSelectedRowByValue(ctrl.datasource.col);
                            }, 650);//temporary solution
                        }
                    }, 650);
                }

 In this case,"data_node" just as  "webcombo1" i said before,"data_table" as "webcombo2" and "data_col" as "webcombo3"."data_node"Combo uses unbound mode,"data_table" linked to "data_node" and "data_col" linked to "data_table".I can confirm the value of webcombo1 has been success set because it's unbound mode.

As you see,i use 2 timeout to delay to set value of "data_table" and "data_col",now it works well but i have to wait for 1.3s ,in fact,if the delay has been set less than 600 which is 0.6s,the error will show to ask me to select "data_table" first.

Please tell me if i did something wrong.