In the latest builds of jdk7u-osx and jdk7u-dev arrow keys are interpreted twice when pressed. This is easy to reproduce in Bugster. Just go to any text input area with some text, click at the beginning of the text, and press the right arrow key. You'll see that the cursor moves ahead two characters.
The same is true for the up and down arrows -- open the 'Priority' popup menu and use the arrows to move up and down in the list. You'll jump ahead or back two lines.
Finally, forward delete is also handled twice, although there's a second bug there in that you see two rectangles in addition to the two characters being deleted.