I've been experiencing this behavior for all versions of Idea I was running - from 4 to 6.
Im my build.xml ant script Idea highlights sub-tasks of webdoclet task as errors (element "strutsconfigxml" is undefined for example). "deploymentdescriptor" itself is not highlighted but it's attributes like "servletspec" are: "attribute is not allowed here".
All tasks run just fine, it's just marking half of build.xml is annoying.
See the attach for example. Am I missing something? I've done my research but could find any hints on what I'm doing wrong.