GLX_EXT_visual_info
http://oss.sgi.com/projects/ogl-sample/registry/EXT/visual_info.txt
	GLX_X_VISUAL_TYPE_EXT 0x22
	GLX_TRANSPARENT_TYPE_EXT 0x23
	GLX_TRANSPARENT_INDEX_VALUE_EXT 0x24
	GLX_TRANSPARENT_RED_VALUE_EXT 0x25
	GLX_TRANSPARENT_GREEN_VALUE_EXT 0x26
	GLX_TRANSPARENT_BLUE_VALUE_EXT 0x27
	GLX_TRANSPARENT_ALPHA_VALUE_EXT 0x28
	GLX_NONE_EXT 0x8000
	GLX_TRUE_COLOR_EXT 0x8002
	GLX_DIRECT_COLOR_EXT 0x8003
	GLX_PSEUDO_COLOR_EXT 0x8004
	GLX_STATIC_COLOR_EXT 0x8005
	GLX_GRAY_SCALE_EXT 0x8006
	GLX_STATIC_GRAY_EXT 0x8007
	GLX_TRANSPARENT_RGB_EXT 0x8008
	GLX_TRANSPARENT_INDEX_EXT 0x8009