This is one of the most useful functions, especially when you work with multiple GUIs in one script. In order for this function work properly, all GUIs in your script should have path to form file. Koda automatically generates this path in the code, when form was saved before. After you reopen you form, script with link to this form should be found. The simplest way to use this function:
After you done, you will see in the form list form icon changed - “script” overlay should be visible. This mean that form now have associated script and update function will generate code in this script (menu item is now enabled). This function generate only clean GUI code (it's part between #region and #endregion).
You can have multiple form definitions in single script. Update function call will update only part of currently active form.
This function also called by pressing Ctrl+U