code: def setExpanded( self, state ):
          
          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)
docs: Sets whether or not this rollout is in the expanded state.
          
          :param      state | <bool>