Sets whether or not this rollout is in the expanded state.
        
        :param      state | <bool>

def setExpanded( self, state ):
        """
        Sets whether or not this rollout is in the expanded state.
        
        :param      state | <bool>
        """
        self._expanded = state
        self._widget.setVisible(state)
        
        if ( state ):
            ico = projexui.resources.find('img/treeview/triangle_down.png')
        else:
            ico = projexui.resources.find('img/treeview/triangle_right.png')
        
        self._titleButton.setIcon(QIcon(ico))
        
        # emit the signals for this widget
        rollout = self.rolloutWidget()
        if ( not rollout.signalsBlocked() ):
            index = rollout.widget().layout().indexOf(self)
            
            rollout.itemCollapsed.emit(index)
            rollout.itemExpanded.emit(index)