I've run this and this is what I get
I don't see an extra button, what is the problem you're having?
That is odd, I've tried it in Eclipse and Netbeans and compiling from command line and each one gives the right output without the extra button at the top so the code is right, there must be something wrong within your Eclipse. I'm not so good with Eclipse (mainly use Netbeans) so can't suggest anything. Has anyone else on here got any suggestions?
Best guess would be that this is a problem with your Java version. Google should be able to tell you which versions are compatible with Win 7 and which might cause problems