To use Widget["ColorChooser"], you first need to load GUIKit using Needs["GUIKit`"].
An instance of Widget["ColorChooser"] can be placed within any user interface definition, and you can bind to the chooser's "selectionModel" to be notified whenever the currently selected color changes.
The following properties are available:
"selectionModel"
DefaultColorSelectionModel
model that intercedes selection operations between the user interface and the data
"color"
white
currently selected color
The "selectionModel" property allows for binding to its "change" event to know when the selected color changes.
EXAMPLES
Basic Examples 
Generalizations & Extensions