Allow clicking on hint-icon to see hint-text

[plbowers]

Currently you can see the hint-text by hovering over, but there is a slight delay before the hover takes effect. Some users might go straight there and click immediately - in that case something sensible should happen which would seem to indicate showing that text.

See http://jsfiddle.net/9mmmwum4/2/ or similar

It would be good if we could figure out a way to make it look the same as the hover-over, but that may get into some browser-dependent code...