gtk-render-focus (context cr x y width height)

context -- a gtk-style-context object
cr -- a cairo-t context
x -- a number, coerced to a double float, with a x origin of the rectangle
y -- a number, coerced to a double float, with a y origin of the rectangle
width -- a number, coerced to a double float, with a rectangle width
height -- a number, coerced to a double float, with a rectangle height

Renders a focus indicator on the rectangle determined by x, y, width, height.