The functionality provided by GUIKit has been superseded by the interface construction
functions native to the built-in Wolfram Language.
GUIKit Example: CellularGroup
This example demonstrates how to create a reusable GUIKit` widget for a cellular automaton.
You can easily treat the CellularGroup example as a single reusable user interface element within other panels, as well as expose widgets within the definition uniquely.
Here we expose the canvas widget with unique names and create a modal result expression extracting the current graphics.