Here's the deal: when you have multiple monitors, the windows mechanic of click+dragging a full screen application's titlebar is the best way to shift applications from screen to screen. With Opera, I just throw my mouse to the top of the screen and drag. With Firefox and Chrome, I have to search out a tiny 20 pixel wide hitbox between the end of the tabs and the minimize button to start the drag action. Every single windows application I've used respects this mechanic, except for Chrome and Firefox. I actually brought this up with the Firefox UI team on reddit and they agreed that it's broken but evidently decided to keep it because people like OP now expect it.
I'm actually looking for a way to enable this on chrome/FF.