Reproduction steps:
1. Open the attached project.
- Editor freezes.
- Editor crashes after a few minutes.

#0 0x000001029271ea in SetupGraphicsContextFromWindow(void*, int, int, bool&)
#1 0x00000102bf3b25 in WindowGLES::Reshape(int, int, DepthBufferFormat)
#2 0x000001019a073a in ThreadedWindow::Reshape(int, int, DepthBufferFormat)
#3 0x0000010290e1b7 in GUIView::Reshape(int, int)
#4 0x00000102926d52 in -[GUIOpenGLView updateGLContext]
#5 0x00000102926ec0 in -[GUIOpenGLView drawRect:]
#6 0x0000010290eacd in GUIView::RepaintAll(bool)

Reproduced with:
5.5.1f1, 5.6.0b5;
OSX 10.11.6

Not reproducible with:
Windows 10 (DirectX and OpenGL)

Note:
Full stack in the edit.