A BuddyPress template tag to display the full length of a message while in threads loop.

gistfile1.php

<?php

/* You can put this in your functions.php or any file that is loaded in the WordPress process 
waiting for a new template tag to be created */

function bp_message_thread_the_content() {
	echo bp_get_message_thread_the_content();
}

	function bp_get_message_thread_the_content() {
		global $messages_template;
		
		/* using the filters of bp_get_message_thread_excerpt as the truncate is not done via filter
		New filters on bp_get_message_thread_the_content might be interesting */
		return apply_filters( 'bp_get_message_thread_excerpt', $messages_template->thread->last_message_content );
	}
	
/* now in your template simply add <?php bp_message_thread_the_content();?> to display the full length of the message. */