How can I use a different gtk theme for eclipse

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http://askubuntu.com – I use a very dark gtk3 theme on my gnome desktop. I am running Ubuntu 12.04 and using the gnome shell. So I use the old gnome interface. How is it possible to use another (a bright one, like the default Adwaita) theme for my eclipse IDE. want eclipse in the bright theme to have a white background and clean buttons etc. Eclipse is written in java so I think a solution can be different for this problem like for other native gtk user interfaces. (HowTos)