Index: _source/plugins/dialog/plugin.js
===================================================================
--- _source/plugins/dialog/plugin.js	(revision 5693)
+++ _source/plugins/dialog/plugin.js	(revision )
@@ -407,7 +407,7 @@
 				setupFocus();
 
 				if ( editor.config.dialog_startupFocusTab
-					&& me._.tabIdList.length > 1 )
+					&& me._.pageCount > 1 )
 				{
 					me._.tabBarMode = true;
 					me._.tabs[ me._.currentTabId ][ 0 ].focus();