Hello, i am wondering how do i make the "Add to cart" button not appear unless a valid set of attribute options is selected ? I am aware that i can setup "Display Only" etc. stuff and i got it to work, but i would prefer the "Add to cart" button to appear on the page only after a certain valid attribute is selected.

Also i would like it to display only when there is quantity available in stock for the current item and the set attributes.

Thanks in advance for any help.