714803 - Firefox does not range check for valid window coordinates at session restore

Status: RESOLVED FIXED

(Firefox :: Session Restore, defect)

Description

[stefan]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1
Build ID: 2011092900

Steps to reproduce:

This bug has happened several times to me, on various Firefox versions and on Windows, Linux and FreeBSD.

Had Firefox open with many tabs, lots of them with Flash content (animations, videos).
Played a youtube video in fullscreen and the bug appeared.



Actual results:

Flash plugin crashed.
When restarting Firefox, browser window(s) were visible for a short moment, then disappearing, being placed outside of the screen. I confirmed by window spy program (forgot which one) on Windows and FvwmIdent on Linux).
These windows were accessible only by maximizing via task bar.
When trying to resize, they "disappeared".
This bug appeared several times over the years, on Windows and Linux machines.

As this particular session was a big one with several browser windows and tabs open that I didn't want to delete, I looked at sessionstore.js and found the following entries:

,"width":1293,"height":972,"screenX":-4662,"screenY":0,"sizemode":"normal",
,"screenX":6384,"screenY":-127,"sizemode":"normal",

After fixing the negative and out-of-range numbers, Firefox displayed the windows correctly at restart.
(See also my posts at http://forums.mozillazine.org/viewtopic.php?f=9&t=2396633&sid=a80da91625967f4ed8a652913417d5a0 )



Expected results:

Firefox should do a simple range checking for valid screen coordinates before moving the windows to the location stored in sessionstore.js after creating them.

By the way, this would avoid the same problem which occurs when the screen resolution is reduced and the Firefox window would be off-screen at the new, lower screen resolution.

Comment 1

[Capt. Frito]

Any progress on this bug? Stefan's report is 100% accurate on Linux (Gentoo, various Firefox versions from my current 10.0.4 all the way back to 3.something). Editing sessionstore.js is the only sure-fire way to fix this for me (I don't use a taskbar with e16/enlightenment).

Comment 2

[robber9]

I've found a simple workaround to restore the screen settings without closing Firefox.  

1.  Open a second Firefox window session (which will usually open in the visible screen area).
2.  Merge the two windows into a single window.  This (usually) merges the two windows into the newly opened visible window and closes the off-screen window.
3.  This will reset the "sessionstore.js" display parameters to all positive values.

Definitely not optimal, but it does avoid the need to completely close the Firefox session and avoids the need to edit the "sessionstore.js" file (definitely not something that the average user would know how to do).  It also allows you to retain all of the open tabs from the existing "invisible" session window.

Comment 3

[Tim Taubert [:ttaubert] (inactive)]

Fixed by bug 864107.