My point is that now that `(setq icomplete-separator "\n")' works (in
most but not all cases), there is no need for the specific
vertical-icomplete implementation anymore. What is (or could be)
needed is an implementation that is "more correct" (correct in all
cases).
I don't totally agree is the same than the branch.
The completion like "compi{compilation" with fido mode is still there,
in the same line and is not intuitive; the ellipsis is not shown and the
{} and [] are still there and hard coded. icomplete-prospects-height is
not respected either because the number of candidates is still
calculated with the window-width and adding the candidates length which
actually makes no sense at all in vertical mode.