I gave up on using the plugin and use FirePHP straight as a mu-plugin
:
And firebug.php
file consists of:
<?php
/*
Plugin Name: FirePHP
Version: 0.1
*/
require_once( 'FirePHPCore/FirePHP.class.php' );
ob_start();
$firephp = FirePHP::getInstance( true );
function logit( $var, $title="From FirePHP:" )
{
global $firephp;
$firephp->log( $var, $title );
}
Then I call it from anywhere (theme, plugin, core) using the function:
logit( $var_to_debug, 'The var contains:' );