This mode has already been done. I wrote this mode almost two years ago and have been updating it ever sense. It works with 3.5 and allows drop down menus and more.
The only difference is that this hack here is all done in the current navbar.
The hack I created adds an addition navbar in your templates so when you want to make changes you do not have to go into the default navbar and worry about messing any code up. All you have to do is create a template for the second navbar and add a hook location in you ADMINCP and add a one line code to you default navbar and you are done.
The one I wrote discusses 4 different locations where the second navbar can go and explains where to put the code for the location you choose.
You can do the same thing as described in this hack and put it in your default navbar. But I find it easy to have a second navbar template to edit. It is your choice.
You can see this more here:
https://vborg.vbsupport.ru/showthrea...8&page=1&pp=15