We've got what is basically a single page web application which uses tabs. There is a Main.aspx page which has a RadTabStrip and a RadMultiPage on it and then, depending on things that a user does in the application, we open up new tabs and place web user controls (.ascx) inside of a new tab and multi-page. Users can switch between tab pages and also close tabs as part of normal application use. The RadTabStrip and RadMultiPage are set up with a RadAjaxManager on the Main.aspx page to be Ajax triggers and updated controls. We also use RadAjaxManagerProxy in some of the ascx pages to control some Ajax postbacks in the ascx pages.
One one of the ascx pages which appears in a tab/multi-page, we've got a RadGrid which has an edit form template defined with a RadAsyncUpload control inside of it. I've set up a Postback Trigger so that only the insert/update button of the edit form template will cause the RadAsyncUpload to save to the uploaded item to the target directory. This works fine as long as I stay on the same tab/multi-page. When I switch tabs to another tab/multi-page, the RadAjaxManager triggers an Ajax postback but the FileUploaded event does not fire server side (which is what I expect). When I switch back to the tab/multi-page with the RadAsyncUpload control on it, the RadAsyncUpload control has lost track of the file and, when I post back with the insert/update button, the RadAsyncUpload control doesn't have a file; the client side state is lost. The temporary file is still in the temporary location but the control doesn't know anything about it so it never gets processed server side.
Is there any way to preserve the state of the RadAsyncUpload across tab/multi-page switches?