Lively4 uses a lot of HTML, CSS, and JavaScript... but what are those little snippets of code that are showing themselves all over the place.
Most of are defined in our own lively.js kitchen sink module.
lively.showPoint(lively.pt(100,100))
lively.showRect(lively.pt(100,100), lively.pt(200,200)).style.backgroundColor = "rgba(0,200,0,0.5)"
lively.showElement(this)
The HTML element returned by those functions can further be used to customize the highlighting.