This is the kind of module I'm looking for, but cannot find it anywhere.
I've just installed the one hacked by cucoket, but it only allows to add submenu of the module who can actually do it by default.

I need something to let me add submenu manually.

Option1-LinkToWhateverItIs/SubOption1-LinkToWhateverItIs
/SubOption2-LinkToWhateverItIs

Option2-LinkToWhateverItIs/SubOption1-LinkToWhateverItIs
/SubOption2-LinkToWhateverItIs

And so on.
If anybody knows, please let me know...
Many Thanks...

The author has released the mutilmenu 1.5, pls check it.

The idea of this is for XOOPS module only (i.e, submenu only shows up if its module is active).

I think some Javascripts Menu will meet your requirement, you can find it by google, or do a search on this site, there are many recommendation about Javascripts Menu.

Many Thanks, I'll try to see what I can Find...