I have a home.aspx file which has a button. when click on this button i would like to do do a modal popup to call login.ascx (user control). i want to make this modal avaiable no matter what page you are on. So if you get timedout, the modal will popup at your current page and ask you to log back in again. so my structural is
primary master - child master - home - user control

i tried to look for a way to do this in telerik modalpopup but haven't found any. Do you guys have any sample like this? Thanks

Hello Duy,

Considering the current session time out you can use a timer, so that on a regular basis, a modal RadWindow will popup with a button which let you perform a callback/an ajax request that in turn will reset the session. The following resources may be helpful in achieving this scenario:
 - Window - Modal Popup - How to configure a modal RadWindow
 - Window - Return Values from a Dialog - Shows how to make a communication between RadWindows.
 - Window - Confirm Dialog Integration - Illustrates how to perform a postback from a RadWindow.

You may also find useful Notification - Session Timeout notification online demo that illustrates how to show a notification with RadNotification control to inform the user that his session is about to expire and to let him continue it if he wants.

Regards,
Danail Vasilev
Telerik