I'm running 10.10 with XCode 6.1 and found that both the 3.0.8 release and the latest (git master) have issues with assertion failures in the demo application when using the OpenGL renderer.
The sequence that reproduces the problem 100% of the time is: 1.) run the freshly built demo (debug mode). 2) Go to the tabs where the OpenGL renderer can be selected and select it. 3) Go to Animations and press the buttons until the assertion happens.
I tried to set the deployment target to 10.7, 10.8 and 10.9 with the same results. I can't compile for 10.10 due to the Point class problem documented in another thread. I'm enclosing a screen shot with the stack trace.
Additionally, an assertion occurs on quit from the demo app. Screen shot included.