1891376 - Tab title wiggles back and forth (saving/not-saving space for favicon) at startup

Status: NEW

(Firefox :: Tabbed Browser, defect, P3)

Description

[Daniel Holbert [:dholbert]]

STR:

1. Start Firefox like so, assuming /tmp/doesnotexist.html is a file that does not exist:

firefox -profile /tmp/foo /tmp/doesnotexist.html

2. Watch the tab title carefully (or record a screencast and play it back in slow motion).

EXPECTED RESULTS:
Stable positioning for tab title, as the tab loads (and ultimately lands on a file-not-found error page). If it needs to move due to presence/absence of favicon, that should happen at-most once.

ACTUAL RESULTS:
We go through these phases, with the title jumping left, right, left, right (via N/Y/N/Y below), i.e. with 3 position-changes between a left-aligned title to a title with space reserved for the favicon:

   Tab title               | Space reserved for favicon? Y/N
1. New Tab                 |        N
2. /tmp/doesnotexist.html  |        Y
3. /tmp/doesnotexist.html  |        N
4. Problem loading page    |        N
5. Problem loading page    |        Y

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: screencast of bug

Comment 2

[Daniel Holbert [:dholbert]]

Attachment: slow-motion playback of attached screencast (10%)

Comment 3

[Daniel Holbert [:dholbert]]

Attachment: screenshot of state #1

I'll attach screenshots of the 5 states that I noted in the table in the initial comment here. Here's state #1 with "New Tab" fully left-aligned (i.e. no space reserved for favicon)

Comment 4

[Daniel Holbert [:dholbert]]

Attachment: screenshot of state #2

Comment 5

[Daniel Holbert [:dholbert]]

Attachment: screenshot of state #3

Comment 6

[Daniel Holbert [:dholbert]]

Attachment: screenshot of state #4

Comment 7

[Daniel Holbert [:dholbert]]

Attachment: screenshot of state #5