A modular, testable, Ruby debugger using some of the best ideas from ruby-debug, other debuggers, and Ruby Rails. Some of the core debugger concepts have been rethought. As a result, some of this may be experimental. This version works only with a patched version of Ruby 1.9.2 or Ruby 1.9.3 and rb-threadframe. See also rbx-trepanning for a version that works with Rubinius.