I would like to have the signal when the color of a vector layer is changed by the user. 
In the doc, there is a signal that seems to fit (http://qgis.org/api/classQgsVectorLayer.html#a403f235d3743aa59bb3aad69a72a5705) but nothing happens when it is called.

I have a method called rendererChanged:
`QObject.connect(self.iface.activeLayer(), SIGNAL("rendererChanged()"), self.DoSomething)`

When executed, my function DoSomething is not executed.

I have also tried :
`self.iface.activeLayer().rendererChanged.connect(self.toto)`

But I get this error :
`AttributeError: 'QgsVectorLayer' object has no attribute 'rendererChanged'`