Hi, I'm on Mac OS X 10.10.5 right now, and I'm using the Intel Iris graphics card (macbook pro retina 13" early 2015). I tested it even on my MacBook Pro mid 2012 with an Nvidia 650M, same stuff.
I use OpenGL 3.3 with C++ on both macs and I've never had this problem.
However, I confirm that the triangle appears after the first resize, but nothing shows up in the console