Index: EditPage.php
===================================================================
--- EditPage.php	(revision 23552)
+++ EditPage.php	(working copy)
@@ -373,7 +373,7 @@
 				$this->formtype = 'diff';
 			} else { # First time through
 				$this->firsttime = true;
-				if( $this->previewOnOpen() ) {
+				if (($this->previewOnOpen() and $wgRequest->getVal( 'preview' ) != 'no') or $wgRequest->getVal( 'preview' ) == 'yes') {
 					$this->formtype = 'preview';
 				} else {
 					$this->extractMetaDataFromArticle () ;