why focusout missing selected option(s)?

Question

i'm using jquery focusin and focusout for expand and minimize a multiple option select on a form:

$("#orgns").focusin(function() 
{ $(this).attr({'size':10}); })
 .focusout(function() 
{ $(this).attr({'size':1}); });

every thing is ok, and 1 line dropdown expands when it's get focus, one or more options is select, and then move to next filed on form. but when return back on drop down and focus on it again the previous selected option is missed. any idea please.