1. An article of manufacture, comprising: a computer readable medium; and instructions stored on the medium that when executed by a processor cause the processor to modify a modeling element palette of a modeling tool by: receiving a graphical user interface (GUI) object definition of a GUI object selected in a GUI application (GAP) external to the modeling tool; generating a GUI modeling element compatible with the modeling tool from the GUI object definition; and adding the GUI modeling element into the modeling element palette.