Avoid adding again components when they are present

Author: extrafu

chrome/content/sogo-connector/calendar/calendar-overlay.js

@@ -239,7 +239,13 @@ function SIOnCalendarOverlayLoad() {
   if (typeof(popup) == "undefined") {
     setTimeout(SIOnCalendarOverlayLoad, 100);
     return;
-  }  
+  }
+
+  let beenhere = document.getElementById("list-calendars-context-sogo-acls");
+
+  if (beenhere != null) {
+    return;
+  }
 
   let properties = document.getElementById("list-calendars-context-edit");
   //let showonly = document.getElementById("list-calendars-context-sogo-showonly");