ccontext:ErrorUnderlinePath -- add squiggly line to path
Synopsis
ccontext:ErrorUnderlinePath(x, y, width, height)
Function
Add a squiggly line to the current path 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/down
segments and the resulting rectangle is centered in the original rectangle.