* to not display unknown tags.
*/
Document createDefaultDocument(Font defaultFont, Color foreground) {
StyleSheet styles = getStyleSheet();
StyleSheet ss = new ScaledStyleSheet();
ss.addStyleSheet(styles);
HTMLDocument doc = new HTMLDocument(ss);
doc.setPreservesUnknownTags(false);
doc.getStyleSheet().addRule(displayPropertiesToCSS(defaultFont, foreground));
doc.setParser(getParser());
doc.setAsynchronousLoadPriority(Integer.MAX_VALUE);