Object-oriented application frameworks present one of the most successful approaches to developing reusable assets in industry, but developing frameworks is both difficult and expensive. Frameworks generally evolve through a number of iterations due to the incorporation of new requirements and better domain understanding. Since changes to frameworks have a large impact on the applications build based on the asset, it is important to assess the stability of a framework. Recently, an approach for assessing framework stability has been proposed [1]. We have extended and applied the assessment approach on one proprietary telecommunication framework and two commercial GUI application frameworks. Based on our findings we formulate a set of hypotheses, which characterize the stability of an object-oriented application framework. We believe these hypotheses to be the most promising ones for further studies of framework stability.