[Nix-dev] Windowmaker not properly defined.

[Berno Strik]

New user of NixOS so bare with me.
I'm running NixOS 14.12.

First:

I've noticed that I can not use:
"services.xserver.windowManager.windowmaker.enable = true".
I get the following error:

error: The option 'services.xserver.windowManager.windowmaker' defined 
in '/etc/nixos/configuration.nix' does not exist.

I've tried to do some research and I think this is because in the 
following file:
"nixpkgs/nixos/modules/services/x11/window-managers/default.nix"

windowmaker is not defined in the imports.
Can someone please look into this problem or help me find a solution.

Second:

Is it also possible to add "libpng" and "libjpeg" to the build inputs.
This is in file 
"nixpkgs/pkgs/applications/window-managers/windowmaker/default.nix".
This allows windowmaker to also use png and jpeg icons. In the current 
build it only supports xpm icons and bitmaps.

Thanks in advance.