Created attachment 70715 [details] Test Suppose we move a<div> to left by setting -webkit-transition:margin-left 1s; margin-left: -100px; Depending on the font and the width of the <div>, smear can be left on screen. Please see the attached test and the screen shot.
Created attachment 70716 [details] Screenshot
Ha, it's leaving text smoothing pixels behind.
This is an example of bug 6274. Note that using "text-rednering: optimizelegibility;" prevents this due to the changes in r57215. *** This bug has been marked as a duplicate of bug 6274 ***
Does bug 6274 cover the case where pixels outside the typographic bounds are touched purely for text smoothing?
(In reply to comment #4) > Does bug 6274 cover the case where pixels outside the typographic bounds are touched purely for text smoothing? The fact that activating the fix for that bug (by specifying optimizelegibility) corrects the test case suggests that the answer is “yes” or “text smoothing on Mac OS X doesn’t ever extend into pixels that lie completely outside the glyph’s optical bounds”.