Something

displaytoggle.tpl

{*
 * $Revision: 1.1 $
 * If you want to customize this file, do not edit it directly since future upgrades
 * may overwrite it.  Instead, copy it into a new directory called "local" and edit that
 * version.  Gallery will look for that file first and use it if it exists.
 *}
{if $user.isRegisteredUser}
<div class="{$class}">
  {capture name=detailMode}
  {if ($theme.detailMode)}
    <a href="{g->url arg1="controller=core.ShowItem" arg2="detailMode=0" arg3="return=1"}">Summary</a> | <span class="active"> {g->text text="detail"} </span>
  {else}
  <span class="active"> Summary </span> | <a href="{g->url arg1="controller=core.ShowItem" arg2="detailMode=1" arg3="return=1"}">{g->text text="detail"}</a>
  {/if}
  {/capture}
  {g->text text="toggle mode: %s" arg1=$smarty.capture.detailMode}
</div>
{/if}

theme.tpl
      {if $theme.pageType == 'album'}
        {g->theme include="album.tpl"}
        {g->theme include="displaytoggle.tpl"}


theme.inc
    /**
     * @see GalleryTheme::showAlbumPage
     */
    function showAlbumPage(&$template, $item, $params, $childIds) {
	$ret = $this->loadCommonTemplateData(
	    $template, $item, $params,
	    array('owner', 'viewCount', 'descendentCount', 'parents', 'peers',
		  'systemLinks', 'itemLinks', 'itemSummaries',
		  'itemDetailFiles', 'thumbnails', 'pageNavigator', 'jumpRange','childItemLinksDetailed'),
	     $childIds);
	if ($ret->isError()) {
	    return array($ret->wrap(__FILE__, __LINE__), null);
	}

	/* Add in our extra stuff */
	$theme =& $template->getVariableByReference('theme');
	$theme['columnWidthPct'] = floor(100 / $params['columns']);

	$detailMode = GalleryUtilities::getRequestVariables('detailMode');
	if ($detailMode != null) {
	    $session =& $gallery->getSession();
	    $session->put('theme.detailMode', $detailMode ? 1 : 0);
        }

	/* Add our header and styles */
	return array(GalleryStatus::success(), 'theme.tpl');

    }