Merge Example

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