Visualise "notification" on tab

[mottosso]

Goal

Help the user understand one or more tabs need attention.

Motivation

When a warning is produced, a red message is printed in the Console tab. But if the user is not actively looking at it, there's no way of telling it happened.

Likewise, when the user environment has been edited, odds are you'll want to be aware of it to avoid unexpected environment edits in your application.

Implementation

Mimic the iOS/Android notification icon.