Bug 130043 [Forms] Content is not allowed in prolog.
When specifying non-"HTML" text to FormText.setText() where parseTags is true "[Fatal Error] :1:1: Content is not allowed in prolog." will be output to stderr. The cause is FormTextModel.parseInputStream() is not setting an error handler on the parser (by default errors are reported to stderr). There are a number of bug reports against Eclipse in general where this type of error is seen (and most of them have been marked as "can't reproduce"). Could someone push out a general announcement to the dev team stating that whenever an XML parser is used, an error handler needs to be set so that these messages don't default to the console?
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/internal/forms/widgets/FormTextModel.java
segment.setHref(href);
			segment.setFontId(boldFontId);
			Node alt = atts.getNamedItem("alt"); 
			if (alt!=null)
				segment.setTooltipText(alt.getNodeValue());			
			segment.setWordWrapAllowed(wrapAllowed);
			return segment;
		} else {
			AggregateHyperlinkSegment parent = new AggregateHyperlinkSegment();
			parent.setHref(href);
			NodeList children = link.getChildNodes();
			for (int i = 0; i < children.getLength(); i++) {
				Node child = children.item(i);
				if (child.getNodeType() == Node.TEXT_NODE) {
					String value = child.getNodeValue();
					TextHyperlinkSegment ts = new TextHyperlinkSegment(
							getNormalizedText(value), settings, null);
					Node alt = atts.getNamedItem("alt"); 
					if (alt!=null)
						ts.setTooltipText(alt.getNodeValue());
					ts.setWordWrapAllowed(wrapAllowed);
					parent.add(ts);
				} else if (child.getNodeType() == Node.ELEMENT_NODE) {
					String name = child.getNodeName();
					if (name.equalsIgnoreCase("img")) { 
						ImageHyperlinkSegment is = new ImageHyperlinkSegment();
						processObjectSegment(is, child, "i."); 
						Node alt = child.getAttributes().getNamedItem("alt"); 
						if (alt!=null)
							is.setTooltipText(alt.getNodeValue());