Currently we just reuse an existing devtools icon for the flexbox highlighter toggle button: the frame picker icon. We should find a proper icon for it. First it can be confusing for people who already know the frame picker icon. And second, I don't think this icon carries the meaning of what flexbox is to users. I have a couple ideas, shown here: https://codepen.io/captainbrosset/pen/pdPmWL?editors=1100