GL_SUN_global_alpha
http://oss.sgi.com/projects/ogl-sample/registry/SUN/global_alpha.txt
	GL_GLOBAL_ALPHA_SUN 0x81D9
	GL_GLOBAL_ALPHA_FACTOR_SUN 0x81DA
	void glGlobalAlphaFactorbSUN (GLbyte factor)
	void glGlobalAlphaFactordSUN (GLdouble factor)
	void glGlobalAlphaFactorfSUN (GLfloat factor)
	void glGlobalAlphaFactoriSUN (GLint factor)
	void glGlobalAlphaFactorsSUN (GLshort factor)
	void glGlobalAlphaFactorubSUN (GLubyte factor)
	void glGlobalAlphaFactoruiSUN (GLuint factor)
	void glGlobalAlphaFactorusSUN (GLushort factor)