plugin generated 1202 characters of unexpected output during activation

I had that too. I also had that with the plugin wp-dashboard-chat

If you notice I think it has to do with how it they construct the class for PHP4 and PHP5 thats causing it to redefine the constructor again

Strict Standards: Redefining already defined constructor for class JCP_UseGoogleLibraries on line 123

Warning: Cannot modify header information - headers already sent by (output started at use-google-libraries/use-google-libraries.php:123) in wp-includes/pluggable.php on line 1121

So if we go to line 123 this is what we get —>

/* PHP 5 Constructor */
Line 123: function __construct()

And right above that —>

/* PHP 4 Constructor */
Line 118: 	function JCP_UseGoogleLibraries() {$this->__construct();}

And on wp dashboard chat —>

Strict Standards: Redefining already defined constructor for class WPDashboardChat in wp-dashboard-chat/wp-dashboard-chat.php on line 47:

LIne 47:	function __construct()

And right above that:

function WPDashboardChat() { $this->__construct(); }

The PHP 4 constructor was for the older version of PHP and I believe PHP5 has the deprecated functions set to generate. I looked in pluggable.php and it’s the AJAX callback check that wordpress verifies to prevent processing requests external of the site.

SO basically it seems like both of these plugins AJAX requests are not getting validated.
For one, we can probably go ahead and delete all PHP 4 references like JCP_UseGoogleLibraries(). This may or may not help. Other than that we probably have to figure out how to get it to validate with the check_ajax_referer but I could be wrong.

This is about as far as I am able to get without trial/error. My PHP is average at best and my ajax knowledge is even worse so hopefully this at least helps shed some light on whats causing the issues for a more experienced developer or the Plugin Author!