Wow, thank you for your answer, it works great !!!
sorry for the bother, but i am actually using an older version of the script, ie:
command! FZFcd :set noquickview | :execute 'cd "'.system('locate $HOME | fzf-tmux --height 10 2>/dev/tty ').'"%IU' | redraw
that uses .system instead of fnameescape, and when run in tmux it doesn't hide vifm when it s run, unlike the command using fnameescape.
would your command also work with the .system command ?
i tried a bit, but didn't get it working,
either way, thanks again