Rated 5 out of 5 stars
I am a Japanese who is using Hide Caption Titlebar Plus.
It is a text in a translation tool.
I will request about change of this tool with a tool.
After this upgrade, when the button has been arranged to the tab bar, a 2-pixel margin came made on the left.
Under the influence of this change, if a mouse cursor is quickly moved to the upper left in the state where only the tab bar is using, it will go into that margin and cannot carry out the browser back smoothly.
Possibly it may be the influence by upgrade of this Firefox.
I am sorry.