Comment 0 for bug 1576052

$ lsb_release -rd
Description: Ubuntu 16.04 LTS
Release: 16.04
$ apt-cache policy firefox
firefox:
  Installed: 46.0+build5-0ubuntu0.16.04.2
  Candidate: 46.0+build5-0ubuntu0.16.04.2
  Version table:
 *** 46.0+build5-0ubuntu0.16.04.2 500
        500 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
        100 /var/lib/dpkg/status
     45.0.2+build1-0ubuntu1 500
        500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

Since the upgrade to version 46.0 using the new gtk3 interface, the scrollbar has been exhibiting behavior inconsistent with previous releases and other gtk apps on the system.

What I expected to happen:
 * Left-click below the scroller to evoke the page down function
 * Left-click above the scroller to evoke the page up function
 * Middle-click on the scrollbar to move the scroller to the cursor position

What happened instead:
 * Left-click moves the scroller to the cursor position
 * Middle-click on the scrollbar does not evoke any reaction
 * Right-clicking on the scrollbar evokes the page up/down function

This not only breaks expected behavior from the previous versions, it's also inconsistent with scrollbar behavior on apps all across the board.