Sets the thread's OpenGL context to the first valid allocated one.
static void CL_OpenGL::set_active( CL_GraphicContext & gc); static void CL_OpenGL::set_active( const CL_OpenGLGraphicContextProvider *const gc_provider); static bool CL_OpenGL::set_active();
Detailed description:
If a valid OpenGL context is not found, then "no render context" is set.