How to add button to Nautilus toolbar in Ubuntu 12.04?

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http://askubuntu.com – How do I add bottons to Nautilus toolbar, such as delete, new folder, cut, paste, etc. In Ubuntu 11.04 I did that by editing the file "/usr/share/nautilus/ui/nautilus-navigation-window-ui.xml", but in 12.04 this file no longer exist. So, how do I do that now? (HowTos)