>> Is it possible to complete zero length string with icicles
>> in other words , is it possible to have in the completion buffer ALL
>> the words avaialbe in ALL buffers and from there starting filtering ?

>
> Not sure what you mean, exactly.
>
> But yes, if you type nothing in the minibuffer when it asks for completion
> input, and you then hit TAB or S-TAB, you should get all available completion
> candidates. This is a common action - it's how you see all possible candidates.
> If you type something, then what you type filters the possible candidates;
> otherwise, you see them all.
>
> However, I don't know what you mean by the last part: "ALL the words available
> in ALL buffers".  Minibuffer completion is available for lots of different kinds
> of object (buffer name, file name, function name, search hit,...). What is the
> context here? What command are you using?
>
> It sounds like you want to complete a word (in a buffer other than the
> minibuffer), using the words that are present in all buffers as candidates. Is
> that correct? Are you referring to `C-M-/', which (in Icicle mode) is
> `icicle-dabbrev-completion'? If so, use `C-h k C-M-/' to see the description of
> this command. In that description, you see that `C-u C-u C-M-/' uses all words
> from all buffers as candidates. (`C-h k' is your friend.)