CWM stands for Composited Windowing Manager. The acronym might be misleading a bit because this refers to a complete 
composited windowing system, not just a window manager, like PWM.

Photon will continue to be QNX's traditional windowing system. However, we will soon be offering a composited windowing 
system as an alternative. Unlike traditional windowing systems that arbitrate access to a single buffer, a composited 
windowing system combines off-screen buffers into one image that is displayed.

The APIs to communicate with this windowing system are all open specifications, e.g. OpenKODE and EGL.