This thesis discusses how a UML2 state machine editor can be integrated with a number of components, including Eclipse. The background for the thesis has been the development and integration of SMach, a UML2 state machine editor plug-in that can run on Eclipse and on Rational Software Modeler. We define a reference model for understanding integration and its various aspects. We give examples of different integration types and discuss how to perform integration. Integrating for multiple platforms may lead to problems due to incompatibilities that prevent using the same source code for all platforms. We discuss the problems that this causes, and how the problems may be reduced. We also look at aspects of different types of editors, and discuss how SMach behaves as an editor, using our conceptual model for editors to compare SMach with other state machine editors.