with js u'll have to control hover events, which... kinda tricky, cuz it fires multiple times and easy to lost. something like that: u got hover event on main menu, then show submenu and moves mouse to it, then got mouse out event on main menu and loses submenu.
Here is a really crude dropdown to get you on the right tracks. I don't suggest using style attributes and that you move them to a different style sheet instead, but this should do the job for now. I would also suggest to add target="_blank" to the fav wiki links, but that's my personal preference.
A nice thing about WDS styles is that they're fairly versatile - a class used in one place can work in others without much fuss. Here's another script version, relying on the local navigation dropdown menu styles:
It works as the wiki navigation menus do, meaning the top of the submenu is positioned even with the top of its parent menu. Is this what you refer to? If you use the change Speedit mentions, the bottom of the submenu is positioned even with the bottom of the parent menu item, and the list will appear upwards from there.
I don't think adding the sticked class to .wds-dropdown-level-2__content will have any effect though - it'll work like default.