Registers a control as a trigger for a postback. This method is used to configure postback controls inside an UpdatePanel control that would otherwise perform asynchronous postbacks.
Assembly: System.Web.Extensions (in System.Web.Extensions.dll)
Use the method to register postback controls inside an UpdatePanel control as triggers. Controls that are registered by using this method update a whole page instead of updating only the UpdatePanel control's content. Registering a postback control with this method outside an UpdatePanel control has no affect because by default these controls do not perform asynchronous postbacks.
You can add the trigger declaratively by using the Triggers element of the UpdatePanel control. In Visual Studio, use the designer's UpdatePanelTrigger Collection Editor dialog box.