/**
     * Displays the specified 'step' of the wizard
     * @param WizardStep $oStep The 'step' to display
     */
    protected function DisplayStep(WizardStep $oStep)
    {
        $oPage = new SetupPage($oStep->GetTitle());
        if ($oStep->RequiresWritableConfig()) {
            $sConfigFile = utils::GetConfigFilePath();
            if (file_exists($sConfigFile)) {
                // The configuration file already exists
                if (!is_writable($sConfigFile)) {
                    $oP = new SetupPage('Installation Cannot Continue');
                    $oP->add("<h2>Fatal error</h2>\n");
                    $oP->error("<b>Error:</b> the configuration file '" . $sConfigFile . "' already exists and cannot be overwritten.");
                    $oP->p("The wizard cannot modify the configuration file for you. If you want to upgrade " . ITOP_APPLICATION . ", make sure that the file '<b>" . realpath($sConfigFile) . "</b>' can be modified by the web server.");
                    $oP->output();
                    return;
                }
            }
        }
        $oPage->add_linked_script('../setup/setup.js');
        $oPage->add_script("function CanMoveForward()\n{\n" . $oStep->JSCanMoveForward() . "\n}\n");
        $oPage->add_script("function CanMoveBackward()\n{\n" . $oStep->JSCanMoveBackward() . "\n}\n");
        $oPage->add('<form id="wiz_form" method="post">');
        $oStep->Display($oPage);
        // Add the back / next buttons and the hidden form
        // to store the parameters
        $oPage->add('<input type="hidden" id="_class" name="_class" value="' . get_class($oStep) . '"/>');
        $oPage->add('<input type="hidden" id="_state" name="_state" value="' . $oStep->GetState() . '"/>');
        foreach ($this->aParameters as $sCode => $value) {
            $oPage->add('<input type="hidden" name="_params[' . $sCode . ']" value="' . htmlentities($value, ENT_QUOTES, 'UTF-8') . '"/>');
        }
        $oPage->add('<input type="hidden" name="_steps" value="' . htmlentities(json_encode($this->aSteps), ENT_QUOTES, 'UTF-8') . '"/>');
        $oPage->add('<table style="width:100%;"><tr>');
        if (count($this->aSteps) > 0 && $oStep->CanMoveBackward()) {
            $oPage->add('<td style="text-align: left"><button id="btn_back" type="submit" name="operation" value="back"> &lt;&lt; Back </button></td>');
        }
        if ($oStep->CanMoveForward()) {
            $oPage->add('<td style="text-align:right;"><button id="btn_next" class="default" type="submit" name="operation" value="next">' . htmlentities($oStep->GetNextButtonLabel(), ENT_QUOTES, 'UTF-8') . '</button></td>');
        }
        $oPage->add('</tr></table>');
        $oPage->add("</form>");
        $oPage->add('<div id="async_action" style="display:none;overflow:auto;max-height:100px;color:#F00;font-size:small;"></div>');
        // The div may become visible in case of error
        // Hack to have the "Next >>" button, be the default button, since the first submit button in the form is the default one
        $oPage->add_ready_script(<<<EOF

\$('form').each(function () {
\tvar thisform = \$(this);
\t\tthisform.prepend(thisform.find('button.default').clone().removeAttr('id').removeAttr('disabled').css({
\t\tposition: 'absolute',
\t\tleft: '-999px',
\t\ttop: '-999px',
\t\theight: 0,
\t\twidth: 0
\t}));
});
\$('#btn_back').click(function() { \$('#wiz_form').data('back', true); });

\$('#wiz_form').submit(function() {
\tif (\$(this).data('back'))
\t{
\t\treturn CanMoveBackward();
\t}
\telse
\t{
\t\treturn CanMoveForward();
\t} 
});

\$('#wiz_form').data('back', false);
WizardUpdateButtons();

EOF
);
        $oPage->output();
    }