Button How to intercept signal from a istance of class into another class

Problem:
I have a main window class
( Attntion: are two distinc classes )

class mywin extends GtkWindow
{
 ...constructor...
...

// Now I Instantiate buttons class  
$three_buttons = new mybuttons()
$vbox -> pack_start($three_buttons,0);  
...... ..etc...
end constructor

function OneFunction()
{
    make something
}

}

class mybuttons extends GtkHbox
{
.... constructor

    $button_a=new GtkButton("Open");
     $this -> pack_start($button_a,0);  

    $button_b=new GtkButton("Run");
     $this -> pack_start($button_b,0);  

    $button_c=new GtkButton("Close");
     $this -> pack_start($button_c,0);  
 
     $close_c->connect("clicked", array($this,"OnClose")); // note 6
     
...... end cosntructor

function OnClose ($widget )
{
Here I would call the function OneFunction() in class where it is Instantiate
How can I make it ???
}

}




Thanks