How to build Qt OpenVG application?

[Kaijun]

I have built Qt/embedded 4.7.4 SDK with OpenVG on, but when I try OpenVG app. example star, the painter always use "raster" type rather than "openvg" type. I have tried the following approaches for omap3 beagleboard embedded system. Neither works,

1. QApplication::setGraphicsSystem("openvg") in main.cpp
2. star -qws -graphicssystem OpenVG -display powervr

How can I get my Widget class to call underlying EGL interface as OpenGL uses QGLWidget class?