personally i would rather they made the scroll bar like in IE, Where it doesn't push content, but it is on top of it so whole page doesn't get pushed slightly if it appear dynamically.
[1] https://addons.mozilla.org/en-us/firefox/addon/stylish/ [2] https://userstyles.org/styles/83431/minimal-floating-scrollb...
These kinds of floating scroll bars really should be the default for all OSes. Presence of scroll bars changing the width of the window contents and causing repaints/reflows is really poor UX in my humble opinion.