EXFO FTB-8500 Series for FTB-200 - Manual (Page 54)

Introducing the Smart User Interface
40 FTB-8500 Series and FTB-8120NGE/8130NGE
Main Window
Exit

For FTB-8510B, FTB-8510G, FTB-8525, and FTB-8535:
The exit button ( X ) closes the current application. If a test is created, a
user confirmation is required before closing the application.

For FTB-8120NGE, and FTB-8130NGE:
The exit button ( X ) switches from the current application to the
Network Analyzer application. If the test is running, a user
confirmation is required to stop the test before switching the
application. The switching puts the application in idle mode meaning
that the test case configuration is kept and will be recovered when
returning to that application.