655609 - random missing/hidden words or blocks of text on pages

Status: RESOLVED WORKSFORME

(Firefox :: General, defect)

Description

[bjwest]

User-Agent:       Mozilla/5.0 (X11; Linux i686; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Build Identifier: Mozilla/5.0 (X11; Linux i686; rv:2.0.1) Gecko/20100101 Firefox/4.0.1

I've noticed individual words as well as entire blocks of text missing in pages.  At first I thought it was poor editing, then after quite a few instances decided it was not.  If I cut and paste the problem area into a text editor, the missing text is relieved.  A Google search shows a similar problem a few years ago in the 3.x branch, but in that problem it appears that highlighting the text on the page would make it appear. Now, it does not, although it is clearly there as cut and paste captures it.

The missing word thing happens quite often on a lot of sites including google searches, slashdot, reddit and techdirt, among others, although I don't recall missing whole blocks other than on techdirt.


Reproducible: Always

Steps to Reproduce:
1. load web page
2.
3.

Actual Results:  
Notice seemingly random words missing throughout the page.

Expected Results:  
All text visible.

I've also noticed that reloading the page, visiting it later or, in the case of a Google search, typing in the same search phrase will result in the same word or block missing.  The word is replaced with a blank space

I've also reported this on the ubuntu buglist as Bug 779364.

Comment 1

[Thomas Ahlblom]

Works for me.
Mozilla/5.0 (X11; Linux x86_64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1

Does the issue still occur if you start Firefox in Safe Mode?
https://support.mozilla.com/en-US/kb/Safe+Mode

How about with a new, empty profile?
https://support.mozilla.com/en-US/kb/Basic+Troubleshooting#w_8-make-a-new-profile

Comment 2

[Thomas Ahlblom]

Adding link to the Ubuntu bug:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/779364

Comment 3

[bjwest]

(In reply to comment #1)
> Works for me.
> Mozilla/5.0 (X11; Linux x86_64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
> 
> Does the issue still occur if you start Firefox in Safe Mode?
> https://support.mozilla.com/en-US/kb/Safe+Mode

Yes, text is still missing in Safe Mode.

> How about with a new, empty profile?
> https://support.mozilla.com/en-US/kb/Basic+Troubleshooting#w_8-make-a-new-
> profile

This got rid of the problem.  After copying over all the important files from the old profile, everything still worked.  Setting up my new profile to my liking also reveled the problem.  Unchecking the 'Allow pages to choose their own fonts,...' checkbox in the Advanced Fonts & Colors settings seems to be what is hiding the text.

Comment 4

[Jonathan Kew [:jfkthame]]

Please provide a screenshot showing the display problem that you're experiencing. Also, giving an example of a static page where you see the problem - rather than a news/blog/search-results page that's likely to have changed by the time a developer tries to look into it - would be helpful. Thanks.

Comment 5

[Thomas Ahlblom]

Reporter, if you visit a page with missing words and use Ctrl + scroll wheel to zoom, does that change which words are missing?

Comment 6

[bjwest]

(In reply to comment #5)
> Reporter, if you visit a page with missing words and use Ctrl + scroll wheel
> to zoom, does that change which words are missing?

No, zooming in and out does nothing.

Further investigation has me to believe the problem is in the font rendering.  As I stated above, not allowing the page to use its own font makes the text hidden.  It seems to be related to italicized text via either '<i>' or '<em>' tags.  Going through sans and serif fonts in the settings, DejaVu (both sans and serif) seems to be the kulprit (is DejaVu the default used by Firefox when serif is selected at the top of the font dropdown?), as any other font (ie freesans or freeserif) does not hide the text. Whether this is the fault of the font or the way Firefox handles it is way beyond my skills.

Comment 7

[[:Aleksej]]

(In reply to comment #6)
> (is DejaVu the default used by Firefox when serif is selected at the top of the font dropdown?)

I think the font is selected by the OS / X.Org / desktop environment. Then I guess it is what fc-match from fontconfig shows. For me, it shows DejaVu:

$ fc-match sans-serif
DejaVuSans.ttf: "DejaVu Sans" "Book"
$ fc-match serif
DejaVuSerif.ttf: "DejaVu Serif" "Book"

and I usually have no problems where I wouldn't notice quickly that some lines of text are overlapping (not sure I've ever seen it happen to individual words or depending on styling). WFM with 4.0.1 for Linux x86_64.

Comment 8

[George Carstoiu]

Mozilla/5.0 (X11; Linux i686; rv:7.0a1) Gecko/20110620 Firefox/7.0a1

WFM also. Considering all the comments, setting the status to Resolved Worksforme

Reporter feel free to reopen if you disagree with my decision.

Thanks!

Comment 9

[:aceman]

Reporter, can you check if those problematic font files (like Dejavu) are accessible to you (have proper permissions to be read by your user)?
See bug 656882 for help how to check it. That bug may be the cause of the problem you are seeing.

Comment 10

[bjwest]

aceman: Yes all files in the font tree are accessible to me, including the DejaVu files.

I'm now using FF 5.0 beta 7, and the problem doesn't seem to be present.  I've been using the betas since b2, but didn't think to check previously. I don't know when it stopped being a problem.