[budatalk]

iogames, no offence, but I think that you are not right for 2 reasons.

I honestly don't know the legal details, so strictly legally speaking you might be 100% right.

But common logically:

1- This is the design of the ON/OFF button, it's not new, and i don't understand how the symbol can be "owned". Although you have done some nice rendering and coloring.
2- Using your logo, or any logo, as an avatar and for non-profit purposes isn't much a big problem. The only reason you should be angry is if someone took your logo and is making profit out of it.

Instead, you should feel flattered, that you did such a good work and people are actually using it as avatar.

You know, on a funny note, I am a Phoenician descendant, and I don't know if you know, but the Phoenicians invented the alphabet, from which all latin, greek, cyrillic, arabic, hebrew alphabets came from. Can you imagine if I am granted royalties for every letter or derived letter used in the world, how much of a fortune I would make?