Remove empty tooltip that shows in conversation panel.

src/net/java/sip/communicator/impl/gui/main/chat/ChatConversationPanel.java

@@ -1108,17 +1108,6 @@ private String processImgTags(String message, String contentType)
     private class MyEditorPane
         extends JEditorPane
     {
-        /**
-         * Create tooltip.
-         */
-        public JToolTip createToolTip()
-        {
-            JToolTip tip = new JToolTip();
-            tip.setComponent(this);
-
-            return tip;
-        }
-
         /**
          * Returns the string to be used as the tooltip for <i>event</i>. 
          *
@@ -1129,7 +1118,7 @@ public String getToolTipText(MouseEvent event)
             if(currentHref != null && currentHref.length() != 0)
                 return currentHref;
             else
-                return "";
+                return null;
         }
     }
 }