If you use Mail you have probably seen the animation when replying to a message. The message seems to slide off the screen. It’s possible to disable this animation:
defaults write com.apple.Mail DisableReplyAnimations -bool YES
Restart the Mail application to make changes affect.
To restore the reply animation in OS X Mail:
defaults write com.apple.Mail DisableReplyAnimations -bool NO
How can you do this in 10.9? I tried the command with ‘0’ instead of ‘-bool yes’ since that’s what a read shows, and it does indeed change the property, but there is no change in the Mail.app behavior.