GL_NV_alpha_to_coverage_dither_control
https://www.khronos.org/registry/OpenGL/extensions/NV/NV_alpha_to_coverage_dither_control.txt
GL_NV_alpha_to_coverage_dither_control

	GL_ALPHA_TO_COVERAGE_DITHER_MODE_NV 0x92BF
	GL_ALPHA_TO_COVERAGE_DITHER_DEFAULT_NV 0x934D
	GL_ALPHA_TO_COVERAGE_DITHER_ENABLE_NV 0x934E
	GL_ALPHA_TO_COVERAGE_DITHER_DISABLE_NV 0x934F
	void glAlphaToCoverageDitherControlNV (GLenum mode)