Publish to stream on dropdown select

require_once (JPATH_ROOT.DS.'components'.DS.'com_jfbconnect'.DS.'helpers'.DS.'facebookhelper.php');
JFBConnectFacebookHelper::init();
$fbclient = JFBConnectFacebookHelper::getFbClient();
if (is_object($fbclient) && $fbclient->user && !$fbclient->users_hasAppPermission("publish_stream")) 
	$onchange = "FB.Connect.showPermissionDialog('publish_stream', function(x){if (x=='publish_stream') document.getElementById('involvement').submit();}); "; // involvement
else // else, just submit
	$onchange = "document.getElementById('involvement').submit();";

The $onchange then goes in the select part of the form:

$form = <<<EOT
<form method="post" action="calendar.php" id="involvement" promptpermission="publish_stream" >
	<input type="hidden" name="op" value="myevent">
	<input type="hidden" name="a&#91;cid&#93;" value="1417">
	<input type="hidden" name="a&#91;userid&#93;" value="2359">
	<span class="contribute"><strong>My Events</strong></span>&#58;
	<select name="a&#91;involvement&#93;" id="ainvolvement" onchange="$onchange" >
	<option value="none" >I will not go to this event</option>
	<option value="visit"  selected="selected">I plan to visit this event</option>
	<option value="compete" >I plan to compete in this event</option>
</form>
EOT;

(btw the form attribute promptpermission="publish_stream" doesn't work. i was hoping for that solution originally...)

and then when the form is submitted, the following code is executed&#58;

$fbmessage = "i will go to this event"; // or similar, depending on value of $a&#91;involvement&#93;
$attachment&#91;'name'&#93; = $event&#91;eventname&#93;;
$attachment&#91;'href'&#93; = "http&#58;//example.com/calendar.php?eid=$a&#91;cid&#93;";
$attachment&#91;'description'&#93; = strip_tags(substr($event&#91;eventdesc&#93;, 0, 200))."...";
if (file_exists("components/com_calendar/images/$a&#91;cid&#93;-s.jpg"))
{
	$attachment&#91;'media'&#93;&#91;0&#93;&#91;'type'&#93; = 'image';
	$attachment&#91;'media'&#93;&#91;0&#93;&#91;'src'&#93; = "http&#58;//example.com/components/com_calendar/images/$a&#91;cid&#93;-s.jpg";
	$attachment&#91;'media'&#93;&#91;0&#93;&#91;'href'&#93; = "http&#58;//example.com/calendar.php?eid=$a&#91;cid&#93;";
}
$attachment = json_encode($attachment);
$action_links&#91;0&#93;&#91;'text'&#93; = $event&#91;eventname&#93;;
$action_links&#91;0&#93;&#91;'href'&#93; = "http&#58;//example.com/calendar.php?eid=$a&#91;cid&#93;";
$action_links = json_encode($action_links);
$fbclient->stream_publish($fbmessage, $attachment, $action_links);