Thanks for you answer.

Well the procedure is complete: C-f moves the point until you reach the 
end of the message and then it changes the prompt. If you do C-e as I 
explained before C-f, the point should already be at the end of the 
message and therefore it can't move further.

I tried to add a slash, the problem is the same, as demonstrated in the 
attached gif.

On 13/07/2022 13:07, Lars Ingebrigtsen wrote:
> Tobias Bora <tobias.bora@gmail.com> writes:
>
>> Dear maintainers,
>>
>> If you enable ido with (setq ido-auto-merge-work-directories-length -1)
>> and evaluate:
>>
>> (read-file-name  "Picture name:" "/tmp" nil nil "defaultname.png")
>>
>> and go at the end of the buffer with C-e (not sure why the cursor is not
>> there by default), and press C-f to come back to a normal file prompt
>> (not using ido),
> Are there some missing bits in this recipe?  `C-f' after eval-ing that
> form just moves point, it doesn't change what's prompted for.
>
> In any case, in Emacs directories are supposed to end with a slash, so
> the correct syntax would be:
>
> (read-file-name  "Picture name:" "/tmp/" nil nil "defaultname.png")
>