WGL_NV_swap_group
http://www.opengl.org/registry/specs/NV/wgl_swap_group.txt
	BOOL wglBindSwapBarrierNV (GLuint group, GLuint barrier)
	BOOL wglJoinSwapGroupNV (HDC hDC, GLuint group)
	BOOL wglQueryFrameCountNV (HDC hDC, GLuint* count)
	BOOL wglQueryMaxSwapGroupsNV (HDC hDC, GLuint* maxGroups, GLuint *maxBarriers)
	BOOL wglQuerySwapGroupNV (HDC hDC, GLuint* group)
	BOOL wglResetFrameCountNV (HDC hDC)
