contextMenus

Added in Office 2010

link - learn.microsoft.com/en-us/previous-versions/office/developer/office-2010/ee691832(v=office.14) 
link - jkp-ads.com/rdb/win/s2/win014.htm 

<contextMenus idMso = "ContextMenuCell" > 
<item gallery id="MyGallery"  /> 
<item splitButton id="----"  /> 
<item menuSeparator id="---"  /> 
</comboBox> 

Attributes (properties)

<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui"> 
   <contextMenus> 
      <contextMenu idMso="ContextMenuCell"> 
         <button idMso="FileSave" insertBeforeMso="Cut" /> 
         <button id="MyButton" label="Toggle Case Upper/Lower/Proper" 
           insertBeforeMso="Cut" 
           onAction="ToggleCaseMacro" 
           imageMso="HappyFace"/> 
 
         <menu id="MySubMenu" label="Case Menu" insertBeforeMso="Cut"  > 
              <button id="Menu1Button1" label="Upper Case" 
                    imageMso="U" onAction="UpperMacro"/> 
              <button id="Menu1Button2" label="Lower Case" 
                    imageMso="L" onAction="LowerMacro"/> 
              <button id="Menu1Button3" label="Proper Case" 
                      imageMso="P" onAction="ProperMacro"/> 
         </menu> 
        <menuSeparator id="MySeparator" insertBeforeMso="Cut" /> 
      </contextMenu> 
   </contextMenus> 
</customUI>