Mult. Choice Questions: Enter key after typing answer point value opens Add Attachment window

Typing a number in the Answer Point Value text box and then hitting Enter key on keyboard opens Add Attachment window. In MySql trunk, this also occurs with Negative Point Value text box.

To Replicate:

1. Create an assessment
2. Insert a Multiple Choice question
3. Type a number in the Answer Point Value text box
4. Hit Enter key on keyboard