diff --git a/htdocs/websites/index.php b/htdocs/websites/index.php
index 3ef79ec01b9..874679892d5 100644
--- a/htdocs/websites/index.php
+++ b/htdocs/websites/index.php
@@ -750,7 +750,7 @@ if (count($object->records) > 0)
 
     if ($action == 'preview')
     {
-        print '<div class="websiteinputurl">';
+        print '<div class="websiteinputurl" id="websiteinputurl">';
         print '<input type="text" id="previewsiteurl" class="minwidth200imp" name="previewsite" placeholder="'.$langs->trans("http://myvirtualhost").'" value="'.$virtualurl.'">';
         //print '<input type="submit" class="button" name="previewwebsite" target="tab'.$website.'" value="'.$langs->trans("ViewSiteInNewTab").'">';
         $htmltext=$langs->trans("SetHereVirtualHost", $dataroot);
@@ -867,26 +867,18 @@ if (count($object->records) > 0)
             $realpage=$urlwithroot.'/public/websites/index.php?website='.$website.'&page='.$pageid;
             $pagealias = $websitepage->pageurl;
 
-            print '<div class="websiteinputurl">';
+            print '<div class="websiteinputurl" id="websiteinputpage">';
             print '<input type="text" id="previewpageurl" class="minwidth200imp" name="previewsite" value="'.$pagealias.'" disabled="disabled">';
             //print '<input type="submit" class="button" name="previewwebsite" target="tab'.$website.'" value="'.$langs->trans("ViewSiteInNewTab").'">';
             $htmltext=$langs->trans("PageNameAliasHelp", $langs->transnoentitiesnoconv("EditPageMeta"));
             print $form->textwithpicto('', $htmltext, 1, 'help', '', 0, 2, 'helppagealias');
             print '</div>';
 
-            if (! empty($object->virtualhost))
-            {
-                $urlext=$virtualurl.'/'.$pagealias.'.php';
-                print '<a class="websitebuttonsitepreview" id="previewpageext" href="'.$urlext.'" target="tab'.$website.'" alt="'.dol_escape_htmltag($langs->trans("PreviewSiteServedByWebServer", $langs->transnoentitiesnoconv("Page"), $langs->transnoentitiesnoconv("Page"), $dataroot, $urlext)).'">';
-                print $form->textwithpicto('', $langs->trans("PreviewSiteServedByWebServer", $langs->transnoentitiesnoconv("Page"), $langs->transnoentitiesnoconv("Page"), $dataroot, $urlext?$urlext:$langs->trans("VirtualHostUrlNotDefined")), 1, 'preview_ext');
-                print '</a>';
-            }
-            else
-            {
-                print '<a class="websitebuttonsitepreview" id="previewpageextnoclick" href="#">';
-                print $form->textwithpicto('', $langs->trans("PreviewSiteServedByWebServer", $langs->transnoentitiesnoconv("Page"), $langs->transnoentitiesnoconv("Page"), $dataroot, $urlext?$urlext:$langs->trans("VirtualHostUrlNotDefined")), 1, 'preview_ext');
-                print '</a>';
-            }
+            $urlext=$virtualurl.'/'.$pagealias.'.php';
+            $urlint=$urlwithroot.'/public/websites/index.php?website='.$website;
+            print '<a class="websitebuttonsitepreview'.($virtualurl?'':' websitebuttonsitepreviewdisabled cursornotallowed').'" id="previewpageext" href="'.$urlext.'" target="tab'.$website.'" alt="'.dol_escape_htmltag($langs->trans("PreviewSiteServedByWebServer", $langs->transnoentitiesnoconv("Site"), $langs->transnoentitiesnoconv("Site"), $dataroot, $urlext)).'">';
+            print $form->textwithpicto('', $langs->trans("PreviewSiteServedByWebServer", $langs->transnoentitiesnoconv("Site"), $langs->transnoentitiesnoconv("Site"), $dataroot, $virtualurl?$urlext:'<span class="error">'.$langs->trans("VirtualHostUrlNotDefined").'</span>'), 1, 'preview_ext');
+            print '</a>';
 
             print '<a class="websitebuttonsitepreview" id="previewpage" href="'.$realpage.'&nocache='.dol_now().'" class="button" target="tab'.$website.'" alt="'.dol_escape_htmltag($langs->trans("PreviewSiteServedByDolibarr", $langs->transnoentitiesnoconv("Page"), $langs->transnoentitiesnoconv("Page"), $realpage)).'">';
             print $form->textwithpicto('', $langs->trans("PreviewSiteServedByDolibarr", $langs->transnoentitiesnoconv("Page"), $langs->transnoentitiesnoconv("Page"), $realpage, $dataroot), 1, 'preview');
@@ -911,6 +903,11 @@ if (count($object->records) > 0)
             {
                 print '<script type="text/javascript" language="javascript">
                     jQuery(document).ready(function() {
+                		jQuery("#websiteinputurl").keyup(function() {
+                            console.log("Website external url modified "+jQuery("#previewsiteurl").val());
+                			if (jQuery("#previewsiteurl").val() != "") jQuery("a.websitebuttonsitepreviewdisabled img").css({ opacity: 1 });
+                			else jQuery("a.websitebuttonsitepreviewdisabled img").css({ opacity: 0.2 });
+                		});
                     	jQuery("#previewsiteext,#previewpageext").click(function() {
                             newurl=jQuery("#previewsiteurl").val();
                             newpage=jQuery("#previewsiteurl").val() + "/" + jQuery("#previewpageurl").val() + ".php";