Hi

To be fair, not having arrow icons can be seen in other applications on Ubuntu as well. For example, LibreOffice, Ubuntu Software and Rhythmbox Music Player all follow the same approach.

Clicking on the non slider part of the scrollbar should move the scroll bar up and down (it does for me in Ubuntu 16.10).

See:

• chrome://global/content/minimal-xul.css

scrollbarbutton[sbattr="scrollbar-up-top"]:not(:-moz-system-metric(scrollbar-start-backward)),
scrollbarbutton[sbattr="scrollbar-down-top"]:not(:-moz-system-metric(scrollbar-start-forward)),
scrollbarbutton[sbattr="scrollbar-up-bottom"]:not(:-moz-system-metric(scrollbar-end-backward)),
scrollbarbutton[sbattr="scrollbar-down-bottom"]:not(:-moz-system-metric(scrollbar-end-forward)) {
  display: none;
}

jrootham said

There are no arrow buttons at the end of the slider, and clicking on the slider (but not on the bar) moves to that part of the page (which is difficult/impossible to estimate) rather than moving one page in that direction.

Firefox since 46.0 has required GTK 3.4 (three.four) or preferably newer to run so as a result it needs a GTK3 theme.

This sounds like you may be using a GTK2 theme as missing scroll arrows is one of the glitches you can encounter along with Firefox looking unthemed. This can be easy to encounter if you use say KDE or XFCE.

If one is running KDE (Plasma) or Xfce, how would they know which gtk version is active? Or change it?