Hi,
I think there is a problem with the vertical tabs bar behavior. I have 2 monitors, the Firefox browser is maximized in the secondary monitor in the right of the main monitor. When I move the cursor to the left to the main monitor, the cursor came across the vertical tabs and make it expanded. But when the mouse leave the screen completely and went to the main monitor, the vertical tabs bar keep showing expanded and cover the content in the browser. I think this is a bug related to the position of the cursor in the screens. But I'm helpless because I don't know how to fix it.
