How can I create a spliter bar in a ribbon split button drop down?

HoriaTudosie

I want to obtain something like this:

My approach was to add buttons in a Split Button:

  <splitButtons>
        <splitButton id ="GFXModule_PairSplitButton">
          <tool refID="GFXModule_ButtonPickup"/>
          <button refID="GFXModule_SplitToolAutomaticButton"/>
          <!--<tool refID="GFXModule_Splitter"/>-->
          <button refID="GFXModule_SplitToolPointButton"/>
          <button refID="GFXModule_SplitToolRectangleButton"/>
          <button refID="GFXModule_SplitToolCircleButton"/>
          <!--<tool refID="GFXModule_Splitter"/>-->
          <button refID="GFXModule_SplitToolBreakButton"/>
      </splitButton>
  </splitButtons>

But I cannot find any way to define spliters or to format a button as a splitter.

What approach should I take?

HoriaTudosie

separator="true" would be enough.