I wouldn't know, I insist on building from the CLI all the time, because IDEs confuse and frighten me. To make matters more confusing, it doesn't happen consistently, so simply re-running the build could potentially fix it. It shows the markup of this XHTML rather than it being rendered. It arguably shows the XHTML markup in the worst way possible: in a tree view (?!) with one row per source lineThe markup isn't even well-formed.