Prevent more than 2 level menus in dashboard?

I investigated the codebase a bit and found a globalMaxDepth option in wp-admin/js/nav-menu.js.

When calling wpNavMenu.options.globalMaxDepth = 1 from the browser console in /wp-admin/nav-menus.php you are no longer able to nest more than one level per drag and drop.

To achieve your goal you can now use admin_enqueue_scripts to add a JS file to your backend which calls this code.

Hope this helps!

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