Tab buttons appear on pages that have no tabs (#23751).

Patch by Edouard Cunibil.

git-svn-id: http://svn.redmine.org/redmine/trunk@15853 e93f8b46-1217-0410-a6f0-8f06a7374b81

public/javascripts/application.js

@@ -385,7 +385,7 @@ function displayTabsButtons() {
       }
     });
     var bw = $(el).parents('div.tabs-buttons').outerWidth(true);
-    if ((tabsWidth < el.width() - bw) && (lis.first().is(':visible'))) {
+    if ((tabsWidth < el.width() - bw) && (lis.length === 0 || lis.first().is(':visible'))) {
       el.find('div.tabs-buttons').hide();
     } else {
       el.find('div.tabs-buttons').show().children('button.tab-left').toggleClass('disabled', numHidden == 0);