tl;dr: Change your bttn Edit to also do a server side click, or change your updatepanel to always update (the second one is an ugly hack) I changed it to always update but it doesn't seem to update.
I set the value on the hidden textbox but I do the postback on the button.
Adding these controls to a page eliminates the need to refresh the whole page with each postback.
Only the contents of the Update Panel control will be updated. NET AJAX controls require specific settings in a web.config file in order to function correctly.
Employee ID = @Selected Employee ID" control is raised.The employee-list user control stores the ID of the selected employee in view state. It makes sure that only the selected employee is highlighted in the control, regardless of which page of data is displayed or of how the list has been sorted. Remember to set the Update Mode to Conditional, otherwise the Update Panel will always be refreshed, not only when there is a postback inside or when a trigger fires.Using the Client ID property of the control will ensure that you get the right ID even if the control is inside a masterpage, a webcontrol, a repeater or whatever might change the ID.