title: ASP.NET - Elements disappear on the design view after updating XAML source
body: <p>I think this is a bug in Visual Studio but again I'll try my chance to get a solution for this. I've recently had a problem with my form elements becoming invisible after editing the XAML source. Let's say I want to add a list item to a dropdownlist. If I do it visualy in the design view there's no problem, but if I directly change it in the XML source all the elements in one of the divs disappear and I get "Error creating control Unknown service tag 'uc1:DatePicker'". (Datepicker is my User Control and I've had a lot of headache with it.). However I can see them in the source. Each time I touch the source I have to close and reopen the aspx page. </p>