HMENU_MENUOBJ contains the count of the actual menu item

To read this value we can use register:count_HMENU_MENUOBJ.

temp.topmenu = HMENU
temp.topmenu {
  1 = GMENU
  1 {
    NO { 
      10 = TEXT 
      10.text.field = title
      10.fontFile = fileadmin/kunde/fonts/washington.ttf
      10.fontColor = #535353
      10.fontSize=12
       
       
      20 =TEXT 
      20.text.data= register:count_HMENU_MENUOBJ
      20.text.wrap= 0| 
      20.fontFile = fileadmin/kunde/fonts/washington.ttf
       
    }
  } 
} 

This snippet was submitted by Florian Bittner (MMC.at) .