qgis_python_colose

# Console Python - QGIS

from PyQt4 import QtGui

def printEnable():
    print "Enable"

li = iface.legendInterface()
layer = iface.activeLayer()
if layer.type() == QgsMapLayer.VectorLayer:
    action = QtGui.QAction( u"My Action", iface.legendInterface() )
    action.triggered.connect( printEnable )
    arg = ( action, "My Plugin Menu", "id1", QgsMapLayer.VectorLayer, False  )
    li.addLegendLayerAction( *arg )
    li.addLegendLayerActionForLayer( action, layer )

# Try Disable
#action.setEnabled(False)