To Work with a Code Item
The Code Editor does not provide facilities you can use in Microsoft
      Visual Studio to develop and debug any source code in customization projects. To start working
      with a Code item in Visual Studio, perform the following instructions:
 - Publish the customization project, as described in Publishing Customization Projects.
After you have published the customization project, the <CodeItemName>.cs file with the item code is placed in the App_RuntimeCode folder of the website.
 - Launch Visual Studio.
 - To open the <CodeItemName>.cs file in Visual Studio, on the main
          menu, click File > Open > File, and select the file in the
            Open File dialog box, which opens.Note: If you need to debug the customization code, you have to open the website instead of the file. See To Debug the Customization Code for details.
 - After you have finished editing the source code of the item, click
            Save to save your changes in the file.
Because the App_RuntimeCode folder contains the customization code that is published, the changes in the file are immediately applied to the application instance.
 - Open or refresh the form that uses the code, to make sure that the business logic has
          been changed for the form.Note: If an error exists in the changed file, the website might be corrupted. You can recover the website, for example, in one of the following ways:
- Debug the code
 - Undo the changes
 - Publish the customization project again to update the files in the App_RuntimeCode folder
 - Delete the file from the App_RuntimeCode folder
 
 - To update the Code item in the customization project, follow the instructions described in To Synchronize Code Changes with the Customization Project.
 
