Style guide issue -- key to open combobox

For http://dev.aol.com/dhtml_style_guide#combobox

Recently I learned that OS X users expect to be able to open a combo box 
with a space bar. This seems reasonable.  Mac users are not likely to know 
about Alt+Down arrow. Space bar is also a little bit "less geeky" than 
Alt+down. Can we support both the space bar as well as Alt+down? 

- Aaron