Zsh: make single file selection smart, stylish, and functionally correct (highlights, completions below cursor, etc)

I would like to have a near-flawless "single file selector" with zsh. So far I haven't seen one in questions as they tend to focus on zle settings for one's command line. Let's say we are writing a single file selector that prompts user to provide a single file in some directory. Below is my beginning code that works but needs multiple improvements: 1. Highlight: current menu selection item should be highlighted with reverse-video. 2. Order: the possible file completions should be shown below the prompt. 3. Prompt stepping: Prompt shouldn't step below after printing possible options above. This is related to 2. 4. Only one: Tab complete only first item, as we are asking for only 1 file name from user, not multiple. (This is what I mean by "functionally correct") 5. Size: If there are more possible completions than can fit below the prompt, that case is handled elegantly. Assume alternate screen, and no screen movement or scrolling available. 6. Bonus: If you could think of yet another nice feature to have for a single file selector, feel free to add. Though it would be nice to have it in a separate listing or with comments to identify how to remove your that from solution for 1-5 above. Note: The answer would be self-contained zsh code. It wouldn't ask user to edit .zshrc or install some zsh extension/plugin/framework/library. Create a file `foofiles.zsh` in a temp directory, chmod and run it:

#!/usr/bin/env zsh
setopt extendedglob
setopt globcomplete
setopt nomenucomplete

mkdir ./foo 2>/dev/null
cd ./foo
touch abcd ebcf gbch ijkl mnop qrst unov wxyz
cd ..

function foofileselector {
    cd ./foo/
    local curcontext=foofileselector:::
    vared -p "Select file: " -c foofile;
    cd ..
}

function _foofileselector {
    _files -W ./foo/
}

zstyle ':completion:foofileselector:*:' insert-tab false completer _foofileselector

autoload -Uz compinit && compinit

foofileselector
[[ -z $foofile ]] && foofile="NIL"
echo "You selected: $foofile"

rm -rf ./foo/

This is how it looks like: This is close ([zim](https://github.com/zimfw/zimfw) 's file completion):