Simscape Multi-Domain Custom Component Icon Colors

The Simscape foundation library now contains multi-domain components where different parts of the icon are displayed in different colors depending on the domain (e.g. the Rotational Electromechanical Converter shown in http://www.mathworks.com/help/physmod/simscape/ug/domain-specific-line-styles.html ).

How do I create icons for custom multi-domain components so that they are displayed like that?

[Jannik Jakobsen]

I have a similar problem. I can't find the rules for how to draw the .svg so that different parts of the svg may be intrepretated with different colours.