<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
   <ribbon startFromScratch="false">
      <tabs>   
          <tab id="tab" label="Подборщик кодов ТНВЭД">
             <group id="Группа_1" label="Наименования">
            <dropDown id="MyDropDown" 
                          sizeString="AAAAAAAAAAAAAAAAAAAAA" 
                          onAction="DropDown_OnAction"> 
              <item id="One" label="Наименование 1"/> 
              <item id="Two" label="Наименование 2"/> 
              <item id="Three" label="Наименование 3"/> 
              <button id="button" label="Прочее" onAction="Button_OnAction" /> 
            </dropDown> 
            </group>   
      </tab>
      </tabs>
   </ribbon>
</customUI>