User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0
Watch the bottom of the line boxes 'Xx' and 'kK'. The baseline of the glyphs are only level when transitioning is happening. Before and after the transition, there is a 2px or 3px difference.
The baseline of the glyphs are only level when transitioning of transform is happening.
Steps to Reproduce:
1. Hover the examples to cause a transition which causes a transformation.
Observed that the baseline of the glyphs is uneven when no transitioning is happening.
The baseline of the glyphs are level when no transitioning is happening
Created attachment 525636 [details]
Three examples, one using Ahem font
Similar to this bug.
When the transitioning of transform is happening, things are layerized; when it's not, you're probably seeing a similar text layout problem as the bug you point out -- except on Windows. (Cairo's idea of text layout with interesting transforms generally seems problematic...)