There is an ugly messagebox shown in case an embedded DTD file for XML merging in ConfigurationListener cannot be found: "Doctype input does not appear to be valid: <!-- Exception scanning External DTD Subset. True contents of DTD cannot be determined. Processing will continue as XMLInputFactory.IS_VALIDATING == false. -->"
This should be catched and replaced by a shorter one. Especially there should be shown the appropriate missing file.
Optionally being able to disable validation at all could be also an option.