JSFiddle - React, Tailwind, and code Playground

HTML

You don't actually need any library in order to do this.<br />
<textarea id="yourText">
</textarea>

<div id="yourToolbar">Toolbar</div>

CSS

#yourText{
    width:75%;
    height: 20ex;
}
#yourToolbar{
    position: absolute;
    top: -1000px;
    left: -1000px;
    background: #aaa;
    padding: 2ex 8ex;
    opacity: 0;
}

JavaScript

//config:
var hide_delay = 2000;//ms
var mx=0,my=0; //mouse x,y
var opacity_hi = .85;


yourText = document.getElementById('yourText');
yourToolbar = document.getElementById('yourToolbar');
var hiding = null;
yourText.addEventListener('mouseenter',function(e){
    setTimeout(function(){
        yourToolbar.style.opacity=opacity_hi;
        //this CSS3 renders faster:
        yourToolbar.style.transform='translate('+(1000+mx-10)+'px,'+(1000+my+10)+'px)';
        yourToolbar.style.webkitTransform='translate('+(1000+mx-10)+'px,'+(1000+my+10)+'px)';
    },hide_delay/2);
    if(hiding != null)
        clearTimeout(hiding);
});
yourToolbar.addEventListener('mouseenter',function(e){
    if(hiding != null)
        clearTimeout(hiding);
});
function hide(){
    hiding = setTimeout(function(){
        yourToolbar.style.opacity=0;
    }, hide_delay);
}
yourText.addEventListener('mouseleave',hide);
yourToolbar.addEventListener('mouseleave',hide);
yourText.addEventListener('mousemove',function(e){
    mx=e.pageX;
    my=e.pageY;
    if(hiding != null)
        clearTimeout(hiding);
});