drag handle at top of firefox browser too limited (tabs use most of top space); add ability to use new left sidebar for dragging firefox in addition to top on desktop
I have multiple displays and drag windows from one display to another often. The top of the Mozilla browser has little of the free space used to drag windows around on the desktop or multiple desktops.
Same situation with multiple windows on one desktop.
This is a feature that I have really liked about Zen-Browser. One of those quality of life little things that is nice to have. I like to bounce between FF and Zen (initially due to Zen having really good vertical tabs before FF), and think that the differences in approach are fun. But this is certainly one of those features that just seems like all browsers should have now that vertical tabs are built-in to basically all of them these days.