GtkButton
   A container widget that emits a signal when clicked on.
  
Object Hierarchy
Direct subclasses
Description
   
    The GtkButton widget is a container widget
    that can hold any valid child widget derived from 
    GtkWidget. The most commonly used child
    widget is a GtkLabel.  This is therefore built
    into the constructor 
    as an optional parameter.
   
   
    The GtkButton widget is mainly used to call
    some function when the button is pressed.
   
   
    To change the label after the button is created, you can use the 
    children() function
    of the container class:
    
//$obj is the button object
$childs = $obj->children();
$childs[0]->set_text('new button title');
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Constructor
 --
   Creates a button.
  
Signals
"enter" 
    Emitted when the cursor is over the button.
   "pressed" 
    Emitted when the button is initially pressed.
   "clicked" 
    Emitted when the button is clicked.
   "released" 
    Emitted when the button is released.
   "leave" 
    Emitted when the cursor leaves the button area.