Prevent opening multiple windows in ASP. NET

This article from: http://code.msdn.microsoft.com/CSASPNETPreventMultipleWind-b1dd2bd6

 Csaspnetpreventmultiplewindows overview use: the project has strates how to detect and prevent multiple windows or tab usage  In  Web applications. demo the sample. Please follow these demonstration steps below. Step  1  : Open the csaspnetpreventmultiplewindows. sln. Step  2  : Expand the csaspnetpreventmultiplewindows web application and press Ctrl + F5 to show the default. aspx. Step  3 : We will see two links on the page. First, you can left click one of them jump to correct Link (like nextlink. aspx and nextlink2.aspx). Step  4  : Then, you can right click these links and choose open in new tab or open in New window, and you will find the link not available. Step  5 : You can even copy the right URL and paste it In The browser address bar For  Test. But you can not achieve your goal. Step  6  : Validation finished. Code logical: Step 1 . Create a C # "  ASP. NET empty Web Application  "   In Visual Studio 2010  Or Visual Web Developer  2010 . Name it As   "  Csaspnetpreventmultiplewindows  "  . Step  2 . Add one folder, " Usercontrols  " . Add two user controls In   This  Folder,  "  Defaultpage. ascx  " , "  Nextpage. ascx  "  . Step  3 . Add five web forms In The root directory, " Default. aspx  " , "  Invalidpage. aspx  "  ,  "  Main. aspx  " , "  Nextlink. aspx  " , "  Nextlink2.aspx  "  . Step 4  . Move defaultpage. ascx user control on default. aspx file and move nextpage. ascx user control on all other files extension name are  "  . Aspx  "  . In defalut. aspx. CS page, we have a method generate unique random number: [Code]  Public   String  Getwindowname (){  String Windowname = guid. newguid (). tostring (). Replace ( "  - " , ""  ); Session [  "  Windowname  " ] = Windowname;  Return  Windowname ;}[ / Code] and window. name will recieve  This Unique String  , We use window. Name to prevent mutiple windows and tabs. [Code] //  Set window. Name property Window. Open ( "  Main. aspx  " , "  <% = Getwindowname () %>  "  );  //  If this window name not equal to sessions, will be goto invalidpage         If (Window. Name! = "  <% = Getwindowname () %> "  ) {Window. Name = "  Invalidpage  "  ; Window. Open (  "  Invalidpage. aspx  " , "  _ Self  "  );}[ / Code] Step  5 . Write the codes like the sample. You canGet More details From Comments In  The sample file. Step  6  . Build the application and you can debug it. References: msdn: User Control http:  //  Msdn.microsoft.com/en-us/library/fb3w5b53.aspx