Submenu items overflow the viewport

Hi,

In our client’s menu we have several submenu’s under the main menu.
The submenu’s on the far right of the main menu are that long, that they fall behind the edge of the browser.
See: https://d.pr/i/gjWp
I vaguely remember seeing menu items being positioned to the left of the drop-down menu when they overflow the viewport. Isn’t this part of the Minicorp theme?
Is there a ready-to-go fix for this?

Thanks in advance,

Jelmer