get_custom_title
Description:
Retrieves the custom title widget of the header.
See set_custom_title.
Parameters:
| this | 
Returns:
| 
           the custom title widget of the header, or null if none has been set explicitly.  | 
      
Retrieves the custom title widget of the header.
See set_custom_title.
| this | 
| 
           the custom title widget of the header, or null if none has been set explicitly.  |