Fixed MaterialPopupMenu

Author: kevzlou7979

src/main/java/gwt/material/design/addins/client/popupmenu/MaterialPopupMenu.java

@@ -74,7 +74,7 @@ protected void onLoad() {
     public void load() {
         $(this).attr("tabindex", "0");
 
-        $(window()).off().on("mouseup", e -> {
+        $(this).off("mouseup").on("mouseup", e -> {
             boolean closest = $(e.target).closest("#" + id).length() == 0;
             if (autoClose && closest) {
                 close();