WGL_NV_swap_group
http://www.opengl.org/registry/specs/NV/wgl_swap_group.txt
WGL_NV_swap_group
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, GLuint *barrier)
BOOL wglResetFrameCountNV (HDC hDC)