A system, computer program and method for developing a graphical user interface (GUI) in a computer program. The invention allows developers to control the properties of interface components according to the state of a program during execution. According to the invention, a GUI development environment may be configured to provide a GUI builder for creating the GUI, display an interface component with at least one interface component property to be instantiated in the GUI, display a property interface to input at least one value for the interface component property in response to an event detectable by the computer program during GUI program execution, and automatically generate GUI program code effectuating the value for the interface component property in response to the event detectable by the computer program during GUI program execution.