Checkbox 2-column/Single-column option lost on edit.

Checkbox 2-column/Single-column option lost on edit.

Steps to reproduce:

1. Create a form with a check box field.
2. Add several values (say 6).
3. Set the layout to 2-column display.
4. On user-input action, modify the list of values available (clear the list and then add new values).
(Application: Imagine a Survey. A user has options "A", "B", "C", "None". If a user clicks on "None", I want the rest of the values to be removed from the list since ZC doesn't allow disabling of individual values).

You'll notice that the 2-column layout option is lost and all the new values appear in a single-column.

-Varun Yagain.