We present a metrics-based study of the evolution of Eclipse, an open source integrated development environment, based on data from seven major releases, from releases 1.0 to 3.3. We investigated whether three of the laws of software evolution were supported by the data. We found that Eclipse displayed continual change and growth, hence supporting laws 1 and 6. Six size indicators, out of eight, closely followed trend models. Four were linear and two superlinear. We found evidence of increasing complexity (law 2) in only two indicators, out of five. At subproject level, size and complexity are not distributed uniformly, and subproject size can be modelled as a negative exponential function of the rank position. We encountered a range of different size and complexity trends across subprojects. Our approach and results can help in evaluating the future evolution of Eclipse, the evolution of other systems and in performing comparisons.