Use backtick syntax for `on` in haddocks?

[Gabor Greif]

In this line one could advertise a cuter syntax for on:

threepenny-gui/src/Graphics/UI/Threepenny/Core.hs

Line 240 in f5413b3

 -- > on click element $ \_ -> ... 

namely

-- > click `on` element $ \_ -> ...

[bradrn]

I've been doing a bit of GTK programming recently; in the gtk3 library they do this but the type of on is flipped to get an even more evocative syntax:

canvas `on` buttonPressEvent  $ canvasMouseHandler