Systray Icon Options dialog appears if you run Systray Icon command from menu of BestCrypt Control Panel.
If Use Recently Mounted List checkbox is marked, BestCrypt remembers names of mounted containers and shows the list in Systray Icon pop-up menu, so that you are able to mount the containers from here. Besides, Recently Mounted group will be created and shown in BestCrypt Control Panel.
You will get the same effect if you set option Use recently mounted list in menu of BestCrypt Control Panel.
When you uncheck the option and Recently Mounted List is not empty, BestCrypt will ask whether you want to destroy contents of the list stored in Windows Registry.