GUI File linking is when a button in one GUI file forces iViewer to load an additional GUI file.

The first time a linked GUI file is loaded, it must be served by a HTTP server.

If the iViewer setting Reload GUI Layout is turned off, once the linked GUI file is loaded for the first time it is stored in the cache and wont need to be downloaded again.

Simply enter the URL to the GUI file into the URL parameter of button properties, replacing http:// with cf://.