Hi there, The Page object at runtime has 3 items in its Controls collection:
+[0]: System.Web.UI.ResourceBasedLiteralControl, contains the markup from the top of the page to the end of the opening body tag.
+[1]: System.Web.UI.HtmlControls.HtmlForm, contains the form element.
+[2]: System.Web.UI.LiteralControl, contains the markup from the closing body tag to the end of the page.
If you add a user control with code this.Controls.Add method, your control will be placed at the end of the array (after the LiteralControl). Meanwhile, there's a dropdownlist control declared in the user control, and the dropdownlist needs to always be in the server form tag. So you need to add the user control to the Controls collection of the form element, but not the Page object. To look for examples with javascript, you simply google for it. Clickety[^]