Bug fix: prevent 'assertion failed' when a block auto reloads: '0' is indeed a valid ID for a display block !!

git-svn-id: http://svn.code.sf.net/p/itop/code/trunk@2205 a333f486-631f-4898-b8df-5754b55c2be0

application/displayblock.class.inc.php

@@ -254,7 +254,7 @@ class DisplayBlock
 	
 	public function RenderContent(WebPage $oPage, $aExtraParams = array())
 	{
-		if (empty($aExtraParams['currentId']))
+		if (!isset($aExtraParams['currentId']))
 		{
 			$sId = $oPage->GetUniqueId(); // Works only if the page is not an Ajax one !
 		}