Calling functions from libcompext in nxagent sounds like a bad idea. Other code locations might well be affected by issues alike to that as well.
We can work around this by using the Xlib-based Window data type on the server-side as well, but this problem is likely a more general one.
In order to silence compiler warnings, we can use a "macro hacks" for overriding an e.g. "Window" type in NXlib.h. See 639a2c3 for an example.