pyqt弹出新对话框，以及关闭对话框获取数据

from PyQt4 import QtGui,QtCoreimport sysclass Web_Browser(QtGui.QDialog):    def __init__(self,parent=None):        QtGui.QWidget.__init__(self)        self.resize(550,400)        open=QtGui.QPushButton('OPEN')        self.connect(open,QtCore.SIGNAL('clicked()'),self.ok)        grid=QtGui.QGridLayout()        grid.addWidget(open,1,0,1,1)        self.setLayout(grid)        self.setWindowTitle('main windows')        def ok(self):        web=Web_Browser()        web.setModal(False)        web.setWindowTitle('sub window')        web.exec_()app=QtGui.QApplication(sys.argv)app.setFont(QtGui.QFont("Helvetica", 16))main=Web_Browser()main.show()sys.exit(app.exec_())