We now support the ability to disable out of stock item attributes. For instance if you sell an item and it comes in small, medium and large but medium is sold out you can make that choice show in the dropdown but not be selectable (ie greyed out).
To change this setting go to
Find the field labelled Out of Stock Item Attributes
Select DISABLE out of stock attributes
There are 2 other choices
SHOW out of stock attributes and HIDE out of stock attributes
SHOW will show the attributes with the word out of stock added to the text.
HIDE will not show the attribute at all, in the example above only the small and large choices would show.