Created attachment 418121 [details]
Consistent reproduction pattern
Redrawing a text element after font family or font size changes can result in pieces of the old draw remaining on screen.
It mainly seems to occur when the updated text has decreased in size in comparison to before the update.
Resizing the window, removing focus from the window or changing style attributes on the text element will clear the remnants of the old draw.
This seems to be dependent on the used font, but can be consistently reproduced (see attachment).
Dupe of bug 6274?
(In reply to Alexey Proskuryakov from comment #1)
> Dupe of bug 6274?
I think you're right. The remaining pixels are exactly the part of the glyph that are outside the bounds of the text. This explains why it does not happen for all fonts. Thanks for taking a look, I'll mark this as duplicate.
*** This bug has been marked as a duplicate of bug 6274 ***