A single button widget for toggling fullscreen mode.
    
    
    
    
    
    
        
| Name | Type | Default | Description | 
|---|---|---|---|
| container | Element | String | The DOM element or ID that will contain the widget. | |
| fullscreenElement | Element | String | document.body | optional The element or id to be placed into fullscreen mode. | 
Throws:
- 
    DeveloperError : Element with id "container" does not exist in the document.
