244437 - [Xft] Some unicode glyphs randomly disappearing and appearing on user interaction

Status: RESOLVED DUPLICATE of bug 190278

(Core Graveyard :: GFX: Gtk, defect)

Description

[Flammie Pirinen]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040508 Firefox/0.8
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040508 Firefox/0.8

When a page containing unicode characters is loaded, some of the characters are
left undisplayed (ie. not even replacements displayed). However, when playing
with text selection all of these become visible, with that oddity that while
other characters in seltext area are white on gray blackground, these invisible
characters might or might not appear in black on gray blackground. Similarly if
I open some other window on top of Mozilla's window some of these characters
disappear and appear at random. 

I'll attach two screenshots related, they aren't the best to demonstrate my
purpose but the problem is that taking of the screenshot using capture also
affects to displayed characters in a somewhat random manner.

Reproducible: Sometimes
Steps to Reproduce:
1. Open page http://www.cogsci.ed.ac.uk/~richard/unicode-sample-3-2.html
2. Scroll, select text, move around, change windows...
3. Watch the characters appear and disappear

Actual Results:  
The characters appear and disappear at random, with most common state being all
characters not showing.

Expected Results:  
Characters showing all the time.

Distribution is Gentoo, the package used is stable, compiled firefox, with
options gnome, gtk2, xinerama and truetype that might relate to problem.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Sounds like an xft bug -- I'm not seeing this with non-xft builds....

Comment 2

[R.K.Aa.]

Confirming. I didn't see any weirdness on the test page untill i had had another
tab in front and then selected the tab with the tests again. Then some fonts
looked like tiny scattered dots, and after selecting those areas several times
actually, the real font appears again.

mozilla current trunk CVS, Gtk2+xft (fedora core2/test3+rawhide)

Comment 3

[R.K.Aa.]

same issue as in bug 232647?

Comment 4

[Flammie Pirinen]

(In reply to comment #3)
> same issue as in bug 232647?

I'd think that 232647 deals more with overall consistency of different fonts in
multilingual pages without proper language markup. It might be related on lower
level though. Also what is said in comment 9 of that bug does not apply to this
problem: I already have subpixel rendering enabled.

I actually thought of making a test page with language markup included, but then
I realized that the problematic are mostly include IPA and math sections of
unicode, and there is no language that I know of which would be properly defined
for such universal glyphs (or perhaps: "und"?).

Ack. I forgot the screenshots, I'll spam them here now.

Comment 5

[Flammie Pirinen]

Attachment: Image with seltext and glyphs showing

Observe the first line of Misc. technical

Comment 6

[Flammie Pirinen]

Attachment: Same image without seltext

Comment 7

[Christopher Blizzard (:blizzard)]

What distro are you using?  This is probably a dup of the hebrew bug which was
fixed with upstream patches a long time ago.

Comment 8

[Flammie Pirinen]

(In reply to comment #7)
> What distro are you using?  This is probably a dup of the hebrew bug which was
> fixed with upstream patches a long time ago.

Distribution is Gentoo as told in the comment #1. Which hebrew bug that might be
then? I didn't find anything obviously related by searching hebrew bugs. 

Although I do think the phenomenon did appear on my Fedora Core 2 install at
work, I'm not sure if it contains more recent version which might have this
patch from long time ago.

Comment 9

[Christopher Blizzard (:blizzard)]

I'm talking about bug 190278.

Comment 10

[Flammie Pirinen]

(In reply to comment #9)
> I'm talking about bug 190278.

Now it definetely seems like the same bug, however I find it strange that the
bug still appears if it indeed has been patched so long time ago. Using ldd
reveals that libxft version is 2.1, and Firefox version should indeed be a
recent 0.8 build.  Any suggestions for further investigation? It might also be
proper to mark this bug as duplicate, but perhaps reopen the older bug?

Comment 11

[Christopher Blizzard (:blizzard)]

I'll bet you still have a buggy library in your path somewhere.

*** This bug has been marked as a duplicate of 190278 ***

Comment 12

[R.K.Aa.]

i see this bug with Fedora2 test3 updated to rawmeat as per May 20th.

Comment 13

[R.K.Aa.]

And Opera does not show the bug