[cairo] cairo png tEXt support?

[ds]

Hello,

I wonder, if the 

cairo_surface_write_to_png

function supports adding additonal information to the image file.

E.g.: The gdk_pixbuf documentation mentions, that the gdk png loader
supports the tEXt key/value pair.

Is there any solution, to add this key from cairo?

Thanks a lot

Detlef