How to Persist a Control's Value/Text Property Between Page Refreshes?

I have two controls of interest on a page: a DropDownList and a Button. If the user presses the button, he gets a popup form which, when completed, causes the base page to completely reload, losing the value in the DropDownList. To clarify, it's a refresh, not a postback. I cannot change it to make it a postback. What is the most straightforward way of persisting the selected value in the DropDownList across this page refresh? I cannot avoid the page refresh, because the data entered in the popup is reflected elsewhere on the base page.

Update

I've cobbled together a tenative solution that I'm not terribly happy with: when the user clicks the button, I use javascript to get the current value of the dropdown and pass that with the querystring to the popup being loaded. When the user clicks "Save" on the popup, which causes the data to be saved then the base page to be reloaded, I first store the querystring value into a Session variable. The base page, on loading, looks at said Session variable. If a value is present, it sets the value 开发者_JAVA百科of the dropdown accordingly and deletes the Session variable.

Although somewhat kludgy, it's the best I can come up with. I know that my Gracious Benefactors dislike using Session variables, but given the page reload, I cannot come up with an alternative. Also, since the Session variable is short-lived, being created shortly before a page is closed then being deleted shortly after the succeeding page is opened, I'm hoping this will be acceptable.

Contrasting opinions, refutating my solution or reasoning, are enthusiastically welcome.

Conclusion

Ultimately, after I described the solution to my Gracious Benefactors, we agreed upon an alternate approach: if a selection is made in the DropDownList, it must be saved before opening the popup. This avoids the whole ViewState problem altogether.

For updated question:

The solution you are trying sounds like it should work. It's not the sort of thing you want to use SessionState for but there are requirements here that make the situation out of the ordinary.

Depending on how you are getting the base page to reload you may be able to add a query string to that which would save you from putting hte value in the SessionState. But I imagine you have probably considered that.

But basically, as Postback values and viewstate are out of the question, SessionState and query strings are you only real option. Oh, unless you are allowed to use HTML5 local storage? (probably not)

From before question update:

If the aspnetForm is being posted back the the value should be persisted automatically by means of the postback values. So the first thing to know is whther your form is going through a postback or if you are refreshing the page in some other way.

If you can't postback the main form then as rockinthesixstring said an Ajax post might be what you need.

Also, if you are doing anything fancy with binding the datasource to the DropDownList or trying to persist the selectedValue yourself then check and re-think that.