var instance = new Vintasoft.Imaging.UI.UIElements.WebUiElementStateJS(name, settings);

var value; // Type: function
value = instance.get_Callback();

function get_Callback() : Function;

Undefined OR A function, which will be called when state become active.
Here is function prototype "function __callback(UIElement)", where "UIElement" parameter is an instance of WebUiElementJS type.