QGLContext::QGLContext ( const QGLFormat & format ) doesn't initialize paintdevice

The docs for QGLContext::QGLContext ( const QGLFormat & format ) say that after I call QGLContext::create() then the context will be ready to use. However, create() bails because d->paintDevice is null. There is no way to set d->paintDevice to a valid pointer through the public API, either.

#include <QtCore/QtCore>
#include <QtGui/QtGui>
#include <QtOpenGL/QtOpenGL>
#include <cassert>

int main(int argc, char* argv[])
{
    QApplication  app(argc, argv);
    QGLContext *cx = 0;
    bool rv;

    cx = new QGLContext(QGLFormat(QGL::SampleBuffers));
    assert(cx);
    rv = cx->create();
    assert(rv);

    return 0;
}

$ g++ -o main `pkg-config --cflags --libs QtCore` `pkg-config --cflags --libs QtGui` `pkg-config --cflags --libs QtOpenGL` main.cpp
$ ../main
main: main.cpp:16: int main(int, char**): Assertion `rv' failed.
Aborted
$

From qgl.cpp (4.7.1):

bool QGLContext::create(const QGLContext* shareContext)
{
    Q_D(QGLContext);
    if (!d->paintDevice)
        return false;
/* ... */