I'm working on an ASP.NET WebForms CMS application, and having a bit of trouble solving a particular problem. For a while now, I've had a menu on the side of the admin console that shows a list of the pages, links, etc that make up the sitemap. Users could click on an entry, bringing up a flyout menu at the point of the mouse click. This menu has options like update page, view page, delete page, etc.
I've been getting some feedback from my users that having to do multiple clicks to get to the update page is becoming tedious, especially when updating many pages at once. What I would like to do is change my application around such that clicking on one of these menu items will open up the update page, and there can be additional options along the top of that page.
The problem is that since the menu of pages can be quite heavy, I don't want to simply navigate to an entirely new page, and I've already got existing and working functionality in individual aspx pages. What I would really like is to have ONLY the main portion of the page, which contains the updating controls, be updated when you click a menu item. Here's a picture to give you an idea of what I'm working with:
So, I would like to have the user be able to click on an item in section #2 and have section #3 be updated with the update controls for that item. I've looked into using a .NET AJAX UpdatePanel, but some controls that I need, such as validation controls, are not compatible with an UpdatePanel.
I need some ideas as to how to go about this. What is the best method? Has anyone done something like this before? Ideally I would like to be able to preserve the existing pages that I've built, because I know that their logic works.