Fixed mouseout on cascade previews

boards/static/js/refpopup.js

@@ -1,5 +1,7 b''
 var LOADING_MSG = "<div class=\"post\">" + gettext('Loading...') + "</div>";
 
+var CLS_PREVIEW = 'post_preview';
+
 function $X(path, root) {
     return document.evaluate(path, root || document, null, 6, null);
 }
@@ -66,7 +68,7 b' function showPostPreview(e) {'
 
         var cln = doc.createElement('div');
         cln.id = 'pstprev_' + pNum;
-        cln.className = 'post_preview';
+        cln.className = CLS_PREVIEW;
 
         cln.style.cssText = 'left:' + x + 'px; top:' + y + 'px';
 
@@ -114,7 +116,7 b' function delPostPreview(e) {'
         });
     } else {
         while (el.nextSibling) {
-            if (el.nextSibling.className.startsWith('pstprev')) {
+            if (el.nextSibling.className == CLS_PREVIEW) {
                 $del(el.nextSibling);
             } else {
                 break;