Merge Example

  file1.ui                          file2.ui
Root                              Root
  menu                              menu
    submenu: FileMenu                 submenu: FileMenu
      menuitem: Open                    separator
    placeholder: TestPlaceholder        menuitem: Quit
    submenu: HelpMenu                 placeholder: TestPlaceholder
      menuitem: About                   submenu: EditMenu
  dockitem: toolbar1                      menuitem: Cut
    toolitem: NewButton             dockitem: toolbar1
                                      toolitem: OpenButton