1. A method for managing an application execution environment comprising a cross-platform application program interface to provide services to applications that run in the application execution environment, the method comprising: maintaining associations between the applications and different versions of the application execution environment installed on a computer, where the associations indicate in which of the different versions of the application execution environment the applications run; and managing the different versions of the application execution environment on the computer based on the associations between the applications and the different versions of the application execution environment in which the applications run.