gtk:render-arrow (context cr angle x y size)

context -- a gtk:style-context object
cr -- a cairo:context-t context
angle -- a number, coerced to a double float, with an arrow angle from 0 to 2 * Pi, being 0 the arrow pointing to the north
x -- a number, coerced to a double float, with the x origin of the render area
y -- a number, coerced to a double float, with the y origin of the render area
size -- a number, coerced to a double float, with the square side for render area

Renders an arrow pointing to an angle.