Firefox opening too many windows at start or session restoration time, occasionally opening three copies of a tab in response to a single Control-Click

Firefox Development
#1

Firefox 55.0.3 (64-bit) on FreeBSD-CURRENT.

2017-09-20 04:24

A test profile with two extensions: Session Restore and Taborama. Performance-oriented testing with a selection of .session files that were copied from my everyday profile.

For a session that had twelve windows, Firefox (PID 61241) attempted to restore twenty-three:

(Screenshots are available, but can not be uploaded at this time.)

Taborama is both experimental and not intended for use with Firefox 55.x, so I assumed a version mismatch issue and treated the incident as negligible.

More recently

Normally: my ‘everyday’ profile starts with one window (two tabs – one of which was pinned before quit, the second is about:profiles (my home page)), then I use the Tools menu to present a Session Manager dialogue.

Abnormally: Firefox frequently starts with two windows.

The second window comprises the pinned tab that is also pinned in the first window. Screenshots available.

Has anyone else observed that problem?

I wonder whether it’s more likely to occur after quitting with more than eight hundred tabs.

Triplication of tabs

Just rarely, a Control-Click will open three adjacent tabs for the same URL. At first I suspected a hardware issue, maybe a failing mouse, but then I observed the issue with the notebook in a different environment (with a different mouse). Screenshots available.

Anyone else?

#2

2017-09-30 10:45:42 – 00:31 on the timeline – there’s an example of unexpected appearance of a second window.

#3

Whilst I don’t have much time to spend on this issue (sorry … and my train of thought was lost around the time of the upload issues involving Discourse), it’s worth mentioning that recently with SeaMonkey there’s occasional duplication of one tab (not always the same tab) at session restoration time.

I’m toying with the possibility of an issue involving KWin with KDE Plasma 5 beta 5.10.95 from Area 51.

#4

For reference only (this type of issue is so rare, it’s not a problem):

2017-10-28 13:12:09 Firefox with 2,103 tabs
2017-10-28 13:12:09 Firefox with 2,103 tabs.png1366×768 250 KB

Actions before today’s incident included:

  • installation of 56.0.2_2,1 from the FreeBSD repository
  • a bug-free first launch of the new Firefox
  • a bug-free append, by Session Manager, of one of fourteen windows from a 56.0.1… session
  • append of twelve of the other windows from the same saved session.

Without counting, I guess that there are twenty-six Firefox windows in the screenshot above.

(The panel of KDE, to the left, is not normally relatively narrow. I widened it only to allow more of each window title to be visible in the shot.)

The subsequent launch of Firefox, with comparable use of Session Manager, was bug-free.