pango:cairo-show-error-underline (cr x y width height)

cr -- a cairo:context-t instance
x -- a number for the x coordinate of one corner of the rectangle
y -- a number for the y coordinate of one corner of the rectangle
width -- a number for the width of the rectangle
height -- a number for the height of the rectangle

Draw a squiggly line in the specified Cairo context that approximately covers the given rectangle in the style of an underline used to indicate a spelling error. The width of the underline is rounded to an integer number of up and down segments and the resulting rectangle is centered in the original rectangle. All numbers are coerced to a double float before being passed to the foreign C function.