Tableselect with dropdown per row
give default value property to select element e.g select form element returns value if select has been checked 

add this attribute 

'#default_value'= 1; 


to every select list and your data to select list must be an array with key and value

$element=array(
'#type'=&gt;'select',
'#default_value'=&gt;1,
'#options'=&gt;array(
         0 =&gt; t('No'),
         1 =&gt; t('Yes'),
    )

);


maybe then you have to render this element array with theme_form_element to your data variable. sorry but i havent enough time to test this solution