JSFiddle - React, Tailwind, and code Playground

HTML

<div class='a'>Hover over this. The window has to be active.</div>
<div class='b'>I'm here!</div>

CSS

body {
    position: relative;
}
div {
    width: 100px;
    height: 100px;
    position: absolute;
}
.a {
    background: #777;
    left: 50px;
    top: 30px;
}
.b {
    display: none;
    background: #000;
    color:#FFF;
    left: 250px;
    top: 100px;
}

JavaScript

$(function() {
        $("div.a").hover(function() {
            $(document).keydown(function() {
                $("div.b").show();
            });
        }, function() {
           $(document).unbind("keydown");
           $("div.b").hide();
        });
    });