import Material 0.2
A tooltip is a label that appears on hover and explains a non-text UI element.
To display a tooltip for your view, simply create an instance of Tooltip, set the text property to your tooltip text, and then set the mouseArea property to your MouseArea or Ink that will trigger the tooltip. If you use a MouseArea, make sure hoverEnabled is set to true.
See the Material Design guidelines for more details: http://www.google.com/design/spec/components/tooltips.html