775203 - Text sometimes gets rendered as bold on TBPL when scrolling

Status: RESOLVED DUPLICATE of bug 709477

(Core :: Graphics, defect)

Description

[(no longer active)]

Load TBPL and scroll slowly and look at the texts for the commit messages.  Sometimes they get bold as you scroll.  A repaint always fixes the problem.  I've also seen this on many other websites, but TBPL is a very easy place for reproducing this.

Comment 1

[Karl Tomlinson (:karlt back Feb 10)]

Ehsan is seeing this with intel drivers and I've seen it intermittently with radeon drivers.  It is not a bold version of the font but fuzzy/thicker text.

Comment 2

[Benoit Jacob [:bjacob] (mostly away)]

I've had this kind of bugs forever with firefox on linux. The problem seems to be that text is rendered twice, so the blackness adds up.

Comment 3

[(no longer active)]

(In reply to comment #2)
> I've had this kind of bugs forever with firefox on linux. The problem seems to
> be that text is rendered twice, so the blackness adds up.

Yeah that seems to describe what I see.  Sorry for the poor use of the word "bold".

Comment 4

[Karl Tomlinson (:karlt back Feb 10)]

Attachment: screenshot

Sometimes the trigger can be repeated so that the effect builds on itself.
This supports the theory that the text is being rendered again each time.
This attachment show the effect after hovering over images above this text on google news.

I've seen this look (but not necessarily the repeated enhancement) in builds as old as 4.0b11 732a38102733 at least, but it was harder to reproduce and disappeared on scrolling.  In more recent builds, as far back as 13.0 at least, the effect remains while scrolling.

Comment 5

[Timothy Nikkel (:tnikkel)]

This sounds a lot like bug 709477.

Comment 6

[Karl Tomlinson (:karlt back Feb 10)]

Bug 709477 has a reduced testcase.  Thanks!