WGL_I3D_digital_video_control
http://oss.sgi.com/projects/ogl-sample/registry/I3D/wgl_digital_video_control.txt
	WGL_DIGITAL_VIDEO_CURSOR_ALPHA_FRAMEBUFFER_I3D 0x2050
	WGL_DIGITAL_VIDEO_CURSOR_ALPHA_VALUE_I3D 0x2051
	WGL_DIGITAL_VIDEO_CURSOR_INCLUDED_I3D 0x2052
	WGL_DIGITAL_VIDEO_GAMMA_CORRECTED_I3D 0x2053
	BOOL wglGetDigitalVideoParametersI3D (HDC hDC, int iAttribute, int* piValue)
	BOOL wglSetDigitalVideoParametersI3D (HDC hDC, int iAttribute, const int* piValue)