| Interface | Description | 
|---|---|
| OnClickListener | Defines an object which listens to click events. | 
| Class | Description | 
|---|---|
| Button | A button is a widget that displays a text and reacts to click events. | 
| ImageButton | An image button is a widget that displays an image and reacts to click events. | 
| ImageWidget | A widget that displays a resource image. | 
| Label | A label is a widget that displays a text. |