In Firefox 29+, you can activate Menu bar which is ~20px high if you want that d...

In Firefox 29+, you can activate Menu bar which is ~20px high if you want that draggable handle: right-click on an empty space in the top row (not occupied by a tab), or a "+" button, and tick "Menu bar".

I'm also using [Win]+[Shift]+arrows for moving between multiple monitors like others suggested.