Tabs navigation

According to the Scriptcase online manual regarding the Menu settings, activating the option “Menu tabs navigation” will show an arrow on the left and right border of the tabs in order to navigate on it, in case more tabs are open than space is present. But activating the option doesn’t take any effect.
Is there anybody who had also this issue and was able to solve it? Is this a bug?

It’s a bug. To substantiate this claim, this feature formerly worked but no longer does in the most recent edition.

Thanks @drcolew for the swift reply!