Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1575633
Description of problem:
When the notification box contains more than 5 items, it is not possible to scroll down using Firefox.

Version-Release number of selected component (if applicable):
Satellite 6.4 Snap 2

How reproducible:
always

Steps to Reproduce:
1. Have a lot of notification items in the notification box. My specific user case was changing the RSS feed address to a custom feed, which added another three feed items to the notification area.
2. Open the notification drawer in Firefox. There is no scrollbar, and using the mouse wheel scrolls the page itself, not the list of notifications.

Expected results:
Notification list should be scrollable in Firefox.

Additional info:
Using Chrome works - the drawer has a scroll bar, and can be scrolled using the mouse wheel or even arrow keys. See the attached screen shots for the comparison.