WGL_ARB_make_current_read
http://www.opengl.org/registry/specs/ARB/wgl_make_current_read.txt
	HDC wglGetCurrentReadDCARB (VOID)
	BOOL wglMakeContextCurrentARB (HDC hDrawDC, HDC hReadDC, HGLRC hglrc)
	ERROR_INVALID_PIXEL_TYPE_ARB 0x2043
	ERROR_INCOMPATIBLE_DEVICE_CONTEXTS_ARB 0x2054
