xmlroff complains too much when an image isn't found:
(xmlroff:1383): libfo-CRITICAL **: g-file-error-quark: Failed to open file '/usr/local/src/download/figures/pysteganography_start_window.png': No such file or directory
Could not load image.
(xmlroff:1383): GdkPixbuf-CRITICAL **: gdk_pixbuf_get_width: assertion `pixbuf != NULL' failed
(xmlroff:1383): GdkPixbuf-CRITICAL **: gdk_pixbuf_get_height: assertion `pixbuf != NULL' failed
(xmlroff:1383): libfo-CRITICAL **: fo_image_get_width: assertion `fo_image->pixbuf != NULL' failed
(xmlroff:1383): libfo-CRITICAL **: fo_length_get_value: assertion `length != NULL' failed
(xmlroff:1383): libfo-CRITICAL **: fo_image_get_height: assertion `fo_image->pixbuf != NULL' failed
(xmlroff:1383): libfo-CRITICAL **: fo_length_get_value: assertion `length != NULL' failed
After failing to find the file, there seems little point in trying to find its height and width, etc.
