from PyQt4 import QtGui, Qsci


class Editor(Qsci.QsciScintilla):
    def __init__(self, parent=None):
        super(Editor, self).__init__(parent)
        self.textChanged.connect(self.onTextChanged)

    def onTextChanged(self):
        print "CHANGED"


def main():
    app = QtGui.QApplication([])

    widget = Editor()
    widget.show()

    app.exec_()


if __name__ == '__main__':
    main()