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