According to the Doxygen docs, you should be able to document a structure like this:

/**
 * A simple structure to demonstrate the netbeans 6.9.1/doxygen problem in
 * documenting structure members.
 *
 * This type is used blah blah.  Lots of detail here about why this structure
 * solves world hunger, clean water, and brings world peace.
 */
struct Foobar {
    int x; /**< member x description */
    int y; /**< member y description */
};


However, when done like this, the popups in netbeans 6.9.1 incorrectly associate the "x" description with member y, and say that "y" has no documentation. There is also some funkiness that when you use a variable instance of this type, for instance

struct Foobar myfoobar;
myfoobar.[user pauses for docs to pop up here]

then the struct definition should pop up with the list of members, and it doesn't quite work that way.  See the attached screen shots.