I need a menu Entry for favourites, but for all emu at once.
After scratching my head a little bit and reading about in internet, i used a not very elegant brute force method that work.

What you need:
1) Display entry in attract.cfg
display favourites
layout your layout
romlist favourites
in_cycle yes
in_menu yes
filter Favourites
rule Favourite equals 1
2) In attractmode turn on plugin UtilityMenu
in the plugin configuration:
item menu text > "Create FAV menu list" (whatever you like)
item menu command > "@createfav.nut
3) in \plugins\UtilityMenu create a file createfav.nut with:
fe.plugin_command("cmd /c call %CD:~0,3%your_attract_directory/Attract/romlists/alssystemfav.cmd", "" );
save and close
4) in /Attract/romlists/ create a cmd file alssystemfav.cmd with:
@echo off
echo ==================================
echo Processing all systems favourites..
echo ==================================
pushd "%~dp0"
if not exist "fav_bkp\" mkdir fav_bkp
if exist favourites.txt (
echo backup favourites
copy favourites.txt fav_bkp\favourites_copy.txt
del favourites.txt
)
echo adding games to new favourites..
echo ----------------------------------
for %%f in (*.txt) do (
echo adding %%f in favourites
for /F "usebackq skip=1 delims=" %%a in ("%%f") do (
echo %%a>> favourites.txt
)
)
if exist favourites.tag (
echo ----------------------------------
echo backup tag
echo ----------------------------------
copy favourites.tag fav_bkp\favourites_copy.tag
del favourites.tag
)
echo ----------------------------------
for %%t in (*.tag) do (
echo adding %%t in tag
for /F "usebackq delims=" %%b in ("%%t") do (
echo %%b>> favourites.tag
)
)
exit
an save
p.s
this batch file make a unique favorite list and a unique favorite tag from all emu roms list and tag
The menu entry favourites point at this favorites list (remember filter favorites on).
4) enjoy. I hope this will help you