I'm seeing frequent bad paints and the caret jump to random positions in Gmail chat. The caret jumping may also be bad painting. This is difficult to capture without a video, but the cursor seems to jump around and the sentence you're typing may partially or completely disappear. OS X 10.8.2 Retina MBP Nightly r141277
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Is https://bugs.webkit.org/show_bug.cgi?id=109077 related do you think?