The functionality provided by GUIKit has been superseded by the interface construction and controls functions native to the built-in Wolfram Language.
GUIKit Example: GraphEditor
Examples
This example demonstrates the benefit of supplementing Wolfram Language functionality with GUIKit user interface elements leveraging existing third-party graph model and editing libraries. GraphEdit widgets take advantage of the Graph expression supported by Combinatorica` and also SparseArray ArrayRules.
The user interface of the graph editing canvas allows you to do the following.
Here is another version run in a modeless session where you can interact with and change the displayed graph.