You can replace
in your example to
or try to do this:
1. Open Preferences dialog and find "XML->XML Catalog" category.
2. Press "Add"
4. Fill "Key" as http://jboss.com/products/seam/pages-2.1.xsd
5. Close all dialogs by Ok button
For existing errors you need to invoke 'Validate' action from context menu in resource tree for whole project or particular file.
Cleaning the project or whole workspace works as well because it triggers validation.
And BTW we have fixed it for JBT 3.1.0 CR2.
thanks Denis. Keep up the good work.