diff --git a/mailnews/base/resources/content/msgMail3PaneWindow.js b/mailnews/base/resources/content/msgMail3PaneWindow.js
index ebe6a0eafa1..b6ef39fd5f9 100644
--- a/mailnews/base/resources/content/msgMail3PaneWindow.js
+++ b/mailnews/base/resources/content/msgMail3PaneWindow.js
@@ -808,6 +808,7 @@ function FolderPaneOnClick(event)
         }
     }
     else if ((event.originalTarget.localName == "outlinercol") ||
+             (event.originalTarget.localName == "slider") ||
              (event.originalTarget.localName == "scrollbarbutton")) {
       // clicking on the name column in the folder pane should not sort
       event.preventBubble();