The issue is that a GLCanvas is always display on top of the other components. I have tested in a simple demo with a standard Canvas which works well.
I haven't found any workaround so I am open to any suggestion to make the GLCanvas work in my use case.
I will be happy to look at the code to find a real solution, but I am not familiar with OSX code. If somebody could point me in the right direction I will try to find a patch to correct this issue.