A system that detects and resolves circular paths within a graphical flow diagram that represents the logical operation of a corresponding application program. The flow diagram is formed by interconnecting symbolic representations that correspond to program objects configured to execute associated functions in response to corresponding triggering events. The functions of the program objects are called upon and executed by the application program at run-time. At the program objects, a busy indicator is established. When a program object is triggered by its respective event, the object first tests its busy indicator to determine whether it is already in the process of executing its associated function. If not, it proceeds to execute its associated function in response to an earlier triggering event. If, however, the object is already in the process of executing its associated function, then the object is blocked from re-executing in response to this new triggering event.