Make Ambiance/Radiance corners less round?

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http://askubuntu.com – I am looking for a way to make the corners of the Ambiance and Radiance themes less round. I don't want theme to be squared corners, but just less round so that I don't see the jagged corners as much. Is there a simple way of doing this? I remember a long time ago there being a slider somewhere to do this, but this might have been on GTK2. (HowTos)