>OpenGL has no RC passed into most functions. It just set's the "current" one globally.
it doesnt need one to be passed by function, nor could it an easily and remain OS/Hardware independant.
>glFlush(); // flush which one?
the one that was last made current by wglMakeCurrent(HDC hdc, HGLRC hrc)
eg. the current RC.
this is pretty much the most efficient and portable way to do it with procedural programming.