The Untangle UI in both v13 and v13.1 aren't always creating or allowing the browser to create scroll bars.
To see this behavior, open something like the remap interfaces UI, then make your browser window very small. And try to use the remap interfaces UI. This came up during a backup / restore operation of one of my boxes. The console was limited to 640x480, and after restore I needed to remap interfaces to get the unit online. This process was made almost impossible due to the inability to see the done, or save buttons.
Another note, it would be really nice if untangle would ask the admin how to remap the interfaces BEFORE it reconfigured them, so the restore doesn't leave you with a busted box.