A software application development system and method of developing and running software is disclosed that allows multiple developers to access, develop and run a common software application simultaneously; even while others are running and using the same software application. In a first aspect of the invention, a software development environment includes combined run mode and design mode functions and code which allow a user to seamlessly toggle between run mode and design mode without compiling or otherwise converting the software application. This is accomplished through the use of common properties tables in both the run mode and the design mode for the application. In a second aspect of the invention, multiple clients of a software application server are each able to develop, run, and otherwise interact with a software application at the same time from different computers so that each modification by each client is reflected immediately in the software application running on each other client. Thus, multiple users can use and develop the same software simultaneously through update notices between the clients and the server. This aspect of the invention allows a software application to be developed and tested by multiple users through a network while a customer is running and commenting on the application from a remote location. Several specific uses for embodiments of the invention are also described.