Is there a way to have the window be moved around while dragging sidebar?

I have been using Zen-Browser as my main, but still use FF daily (both PC and Android). One thing that I have really liked with Zen is that I can move the window around by holding left-click just like the normal toolbar.

Does anyone know if there is a setting or about:config option that can enable this on FF? It has just been such a randomly nice thing to have, but not a big issue if not. Both browsers serve different folks and have their own goals.