Tweak thread animation

Comments don't animate in if there is already a drawer open.

![ghost-new](https://cloud.githubusercontent.com/assets/1572205/2905691/9cb6042c-d607-11e3-8548-29310d34a12d.gif)

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Before:
![ghost-old](https://cloud.githubusercontent.com/assets/1572205/2905696/ae2226a0-d607-11e3-8baf-96c8816eaaeb.gif)