305146 - Dynamically updated CSS background images do not refresh when page is reloaded

Status: RESOLVED WORKSFORME

(Firefox :: General, defect)

Description

[Norbert Stoop]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8b3) Gecko/20050712 Firefox/1.0+
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8b3) Gecko/20050712

Dynamically generated images which are included as CSS background-image are not
redrawn (but requested successfully from server) when the page is reloaded in
the following manner:

I have a mod_perl module which picks a random image every 60 seconds. To allow
caching, it sets the Expires header to about 60 secs in the future. 
I then include that image in a CSS background-image property - nothing
spectacular yet.
If I push the "Refresh" button, everything works: The background image is
refreshed and FF shows a different image every 60 secs. However, if I just
select the location bar and hit enter, the image stays the same all the time.

An ethereal dump of the http traffic shows that FF actually requests the image
from the server if the image's Expires header require so. The server then
correctly sends back the _new_ image, but FF still draws the old one. If I
'reload' the page by hitting 'Enter' in the location bar again, the new image is
finally shown.
The same happens if I click on a link in that page which refers to the page itself.
This is not extremely annoying, but to me it just looks rather odd, since the
image is requested correctly, but somehow it's still the old image which will be
drawn.

Reproducible: Always

Steps to Reproduce:
Hm, that's a bit tricky to reproduce. Maybe use tcpdum/ethereal etc. while
visiting http://vitus.ch/ . The large horizontal image is dynamically picked
from a pool of three images, every 60 secs. 
Wait at least 60 secs, then 'reload' the page by hitting 'Enter' in the location
bar (or by clicking on "Home" in the top navigation bar of the site).


Actual Results:  
The traffic dump shows that FF successfully requests and receives the new image
data. However, the image on screen won't change.

Expected Results:  
FF does not only request and receive the image, but also draw it instead of the
old one.

Same behaviour is also present in FF 1.0.4 (Debian version) and FF 1.0.6
(Windows 2K). Other browsers (Opera 8, IE 6) show the same tcpdump, but draw the
image correctly.

Comment 1

[Frank Wein [:mcsmurf]]

WFM with a current CVS trunk build here (and also with Deer Park Alpha 2).

Comment 2

[Peter van der Woude [:Peter6]]

Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8b4) Gecko/20050818
Firefox/1.0+ ID:2005081823

WFM

Comment 3

[Norbert Stoop]

Attachment: Ethereal dump including some remarks

Comment 4

[Norbert Stoop]

Hm, strange. Same problematic behaviour with Deerpark Alpha 2 on another machine
in a completely different network... My attachment is a sample output from
ethereal to outline the exact problem. I hope it is reproducible by others now.
BTW: Thanks for the great response time!

Comment 5

[Gabriel Sjoberg]

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b4) Gecko/20050831
Firefox/1.0+ ID:2005083106

WFM

Comment 6

[Norbert Stoop]

Ok, latest nightly build (Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9a1)
Gecko/20050901 Firefox/1.6a1) makes this bug showing up only _very_ sporadic.
After two hours of investigating it, I could not find a way to repeatedly
reproduce it. Whatever happened to the code base of the latest version, it
helped, and now works even on my machines (almost always) :-) Thanks, Norbert