I was quite gutted that balupton's excellent show / hide posts plugin doesn't work with the most recent versions of b2evolution so I was thinking of ways to do something similar when I came up with this. It could be used as a spoiler protection too, but it would work best on several lines of content as it wraps the hidden parts in a div container, not a span. So far it's been tested in 2.4.2 and seems to work ok with both Firefox 2 and Safari (not tried IE yet) - assuming the user has javascript enabled.

I really am a novice, at both PHP and javascript, so I'd welcome any thoughts. Feel free to hack away at my code and improve it (but let me know, so I can see what I missed! =))

You can download it [url=http://www.theriomorphous.co.uk/blog/media/blogs/all/abracadabra_plugin.zip]here [/url]and read more about it [url=http://www.theriomorphous.co.uk/blog/darkarts/?title=abracadabra-1&more=1&c=1&tb=1&pb=1]there[/url].

Teh poetry is:

<?php
/*
 * Plugin Name: Abracadabra
 * By Loup, Theriomorphous  - {@link http://www.theriomorphous.co.uk/}
 *
 *
 * b2evolution - {@link http://b2evolution.net/}
 *
 * @package plugins
 */
if( !defined('EVO_MAIN_INIT') ) die( 'Please, do not access this page directly.' );

/**
 * Fades a div into view and out of view using an anchor.
 *
 * @package plugins
 */


class abracadabra_plugin extends Plugin
{
	var $code = '_abracadabra';
	var $name = 'Abracadabra';
	var $priority = 80;
	var $apply_rendering = 'stealth';
	var $group = 'Theriomorphous';
	var $author = 'Loup';
	var $help_url = 'http://www.theriomorphous.co.uk/blog/darkarts/?title=abracadabra-1&more=1&c=1&tb=1&pb=1';  
	var $short_desc='Shows and hides a div.';
	var $long_desc='Fades a div into view and out of view using an anchor.';
	var $version = '1.0';
	var $number_of_installs = 1;

	/**
	 * Init
	 */

	function PluginInit( & $params )
	{
		$this->short_desc = T_('Shows and hides a div.');
		$this->long_desc = T_('Fades a div into view and out of view using an anchor.');
	}


	/**
	 * Perform rendering
	 *
	 * @see Plugin::RenderItemAsHtml()
	 */


	function RenderItemAsHtml( & $params )
	{

	// generate random string

		$chars='abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
		$string = '';
		for($i = 0; $i <= 5; $i++) 
		{
			$string .= $chars[rand(0,strlen($chars)-1)];
		}
		$content = & $params['data'];
		$div_id = 'abra_' . $string; 
	
	// get the anchortext
	
	$content = preg_replace( '¤\[Abracadabra:(.+?)]¤', '<a href="javascript: void(0)" onClick="$(\'#' . $div_id . '\').toggle(\'fade\');return false;">\\1</a>[Abracadabra]' , $content );

	// opening tag
	$content = str_replace					
				( 
					'[Abracadabra]', '<div style="display:none;" id="' . $div_id . '">', $content
				);
	// closing tag
	$content = str_replace 					
				( 
					'[Piffpaffpoof]', '</div>' , $content
				);

	return true;
	}


	/**
	 * Perform rendering for XML feeds
	 *
	 * @see Plugin::RenderItemAsXml()
	 */


	 function RenderItemAsXml( & $params )
	   {
	      $return_this = $this->RenderItemAsHtml( $params ); 

		/*
		*/
		
	   } 


	function SkinBeginHtmlHead( $params = array() )
	{	
		echo 
		'<script type="text/javascript" src="' . $this->get_plugin_url() . '"js/jquery.js"></script>' . "\n" .
		'<script type="text/javascript" src="' . $this->get_plugin_url() . '"js/jquery.dimensions.js"></script>' . "\n" .
		'<script type="text/javascript" src="' . $this->get_plugin_url() . '"js/fx.js"></script>' . "\n" .
		'<script type="text/javascript" src="' . $this->get_plugin_url() . '"js/fx.fade.js"></script>' . "\n";
	}


	function AdminEndHtmlHead()
	{
		$this->SkinBeginHtmlHead();
	}

	function AdminDisplayToolbar( & $params )
	{
		if( $params['edit_layout'] == 'simple' )
		{	// This is too complex for simple mode, don't display it:
			return false;
		}

		echo '<div class="edit_toolbar">';
		echo '<input type="button" id="abracadabra_button" title="'.T_('Abracadabra').'" class="quicktags" value="'.T_('Abracadabra').'" onclick="createtag();" />';
		echo '</div>'; // surely ????

	
?>
		<script type="text/javascript">
			//<![CDATA[
			function createtag ()
			{
				var anchortext = prompt( 'Text for anchor:', 'Read More');
				if (anchortext)
				{
					textarea_wrap_selection( b2evoCanvas, '[Abracadabra:'+anchortext+']', '[Piffpaffpoof]', 0 );
				}
			}
			//]]>
		</script>


<?php
		return true;
	}

}

?>

Requires the enchant libraries (some parts included in zip, to be honest I didn't know which js files, if any, weren't essential, so I left the four most important looking ones in =)).