* @param model the configuration set of the background images.
*/
public Model(ConfigSet model) {
try {
for (int i = 0; i<model.getSize(); i++) {
CGImage image = (CGImage)model.getElementAt(i);
String path = sd.xStringSubstitution.substituteVariables(image.cp_Href,false);
if (fileAccess.exists(path,false))
addDir(path);
else
remove((String)model.getKey(image));