PyQt QAbstractListModel seems to ignore tristate flags

I've been trying for a couple days to figure out why my QAbstractLisModel won't allow a user to toggle a checkable item in three states. The model returns the Qt.IsTristate and Qt.ItemIsUserCheckable in the flags() method, but when the program runs on开发者_开发问答ly Qt.Checked and Qt.Unchecked are toggled on edit.

class cboxModel(QtCore.QAbstractListModel):
    def __init__(self, parent=None):
        super(cboxModel, self).__init__(parent)
        self.cboxes = [
            ['a',0],
            ['b',1],
            ['c',2],
            ['d',0]
        ]

    def rowCount(self,index=QtCore.QModelIndex()):
        return len(self.cboxes)

    def data(self,index,role):
        if not index.isValid: return QtCore.QVariant()
        myname,mystate = self.cboxes[index.row()]
        if role == QtCore.Qt.DisplayRole:
            return QtCore.QVariant(myname)
        if role == QtCore.Qt.CheckStateRole:
            if mystate == 0:
                return QtCore.QVariant(QtCore.Qt.Unchecked)
            elif mystate == 1:
                return QtCore.QVariant(QtCore.Qt.PartiallyChecked)
            elif mystate == 2:
                return QtCore.QVariant(QtCore.Qt.Checked)
        return QtCore.QVariant()

    def setData(self,index,value,role=QtCore.Qt.EditRole):
        if index.isValid():
            self.cboxes[index.row()][1] = value.toInt()[0]            
            self.emit(QtCore.SIGNAL("dataChanged(QModelIndex,QModelIndex)"),
                      index, index)
            print self.cboxes
            return True
        return False

    def flags(self,index):
        if not index.isValid():
            return QtCore.Qt.ItemIsEditable
        return QtCore.Qt.ItemIsEnabled | QtCore.Qt.ItemIsEditable |     QtCore.Qt.ItemIsUserCheckable | QtCore.Qt.ItemIsTristate

You can test it with this,

class MainForm(QtGui.QMainWindow):

    def __init__(self, parent=None):
        super(MainForm, self).__init__(parent)

        model = cboxModel(self)

        self.view = QtGui.QListView()
        self.view.setModel(model)

        self.setCentralWidget(self.view)


app = QtGui.QApplication(sys.argv)
form = MainForm()
form.show()
app.exec_()

and see that only 2 states are available. I'm assuming there's something simple I'm missing. Any ideas? Thanks!

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You may need to create a custom slot on the clicked() signal that cycles through the three states. Generally, tri-state elements are only able to be clicked on and off directly, and are only in the partially checked mode if sub-elements are in different states.

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Looks like it's a known issue, check here:

108755 - Qt::ItemIsTristate fails to set checkboxs within a model view to being Tristate