I have attached a QMenu to the QToolButton in which the Menu is not reflecting correctly.
I am populating my QMenu from reading a .txt file. The menu is showing the correct items on the first run, but if I made changes in the .txt file and re-clicked on the button, the QMenu is still showing the item on the first run.
Adding on, it seems that the clicked signal is only being called once?
class MyWin(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MyWin, self).__init__()
central_widget = QtGui.QWidget()
self.setCentralWidget(central_widget)
vlay = QtGui.QVBoxLayout(central_widget)
hlay = QtGui.QHBoxLayout()
vlay.addLayout(hlay)
vlay.addStretch()
self.add_button = QtGui.QToolButton()
self.tab_bar = QtGui.QTabBar(self)
self.add_button.setIcon(QtGui.QIcon('add.png'))
self.add_button.clicked.connect(self.set_menu)
#self.add_button.setMenu(self.set_menu())
#self.add_button.setPopupMode(QtGui.QToolButton.InstantPopup)
self.tab_bar.setTabButton(
0,
QtGui.QTabBar.ButtonPosition.RightSide,
self.add_button
)
hlay.addWidget(self.add_button)
hlay.addWidget(self.tab_bar)
def set_menu(self):
with open('/Desktop/item_file.txt') as f:
menu_options = f.read().splitlines()
print menu_options
qmenu = QtGui.QMenu(self.add_button)
for opt in menu_options:
qmenu.addAction(opt, partial(self.set_new_tab, opt))
self.add_button.setMenu(qmenu)
self.add_button.setPopupMode(QtGui.QToolButton.InstantPopup)
def set_new_tab(self, opt):
self.tab_bar.addTab(opt)
When a Menu is established in the QPushButton, the mousePressEvent event no longer reaches the QPushButton but is intercepted by the QMenu so the clicked signal is not emited.
One solution is to set a QMenu by default and use the aboutToShow signal to call set_menu that will add the QActions.
On the other hand they are the same because clicked is not issued and therefore set_menu is not called, and even if you call set_menu as I have established it is better to reuse than create so in this case I eliminate the previous QActions with clear method.
from functools import partial
from PyQt4 import QtCore, QtGui
class MyWin(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MyWin, self).__init__()
central_widget = QtGui.QWidget()
self.setCentralWidget(central_widget)
vlay = QtGui.QVBoxLayout(central_widget)
hlay = QtGui.QHBoxLayout()
vlay.addLayout(hlay)
vlay.addStretch()
self.add_button = QtGui.QToolButton()
self.tab_bar = QtGui.QTabBar(self)
self.add_button.setIcon(QtGui.QIcon('add.png'))
self.qmenu = QtGui.QMenu(self.add_button)
self.add_button.setMenu(self.qmenu)
self.add_button.setPopupMode(QtGui.QToolButton.InstantPopup)
self.qmenu.aboutToShow.connect(self.set_menu)
self.tab_bar.setTabButton(
0,
QtGui.QTabBar.ButtonPosition.RightSide,
self.add_button
)
hlay.addWidget(self.add_button)
hlay.addWidget(self.tab_bar)
#QtCore.pyqtSlot()
def set_menu(self):
with open('/Desktop/item_file.txt') as f:
menu_options = f.read().splitlines()
self.qmenu.clear()
for opt in menu_options:
self.qmenu.addAction(opt, partial(self.set_new_tab, opt))
def set_new_tab(self, opt):
self.tab_bar.addTab(opt)
if __name__ == '__main__':
import sys
app = QtGui.QApplication(sys.argv)
w = MyWin()
w.show()
sys.exit(app.exec_())
Related
What I want to do is to open a new Countrypage sub-window by clicking on the "New" button which is in Countrypage itself.
For example, if I click the "New" button in a CountryPage window (window title: "Country page"), one more new Countrypage window will be opened in the MDI area (window title: "Country Page 1"). Now if we click the "New" button in "Country Page 1", one more new window will open in the MDI area (window title: "Country page 2") and so on - and I want to close the windows one by one by pressing the corresponding "Close" button in Countrypage. New window are opened only by pressing a "New" button.
And if we close the last opened window by pressing the "Close" button, the text item in the "Country" text-box will be automatically updated in the previous window's "Country" text-box and so on.
Main Script :
import sys,os
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from sample_countrypage import Countrypage
class MainPage(QMainWindow):
count = 0
def __init__(self):
super().__init__()
self.mdi = QMdiArea()
self.mdi.setFixedSize(1000,400)
self.mdi.setHorizontalScrollBarPolicy(Qt.ScrollBarAsNeeded)
self.mdi.setVerticalScrollBarPolicy(Qt.ScrollBarAsNeeded)
self.setWindowTitle(" Sample Programme")
self.setGeometry(100,100,1600,600)
self.Ui()
self.show()
def Ui(self):
self.btn1=QPushButton("Country")
self.btn1.setFixedSize(100, 30)
self.btn1.clicked.connect(self.countrypage)
self.left_layout = QVBoxLayout()
self.right_layout = QHBoxLayout()
self.main_layout = QHBoxLayout()
self.left_layout.setContentsMargins(3,5,5,3)
self.left_layout.addWidget(self.btn1)
self.left_layout.addStretch()
self.right_layout.addWidget(self.mdi)
self.main_layout.setSpacing(5)
self.main_layout.setContentsMargins(0,0,0,0)
self.main_layout.addLayout(self.left_layout)
self.main_layout.addLayout(self.right_layout)
self.main_layout.addStretch()
widget = QWidget()
widget.setLayout(self.main_layout)
self.setCentralWidget(widget)
self.subwindow1 = QMdiSubWindow()
self.subwindow1.setObjectName("SubWindow_1")
# self.subwindow1.setWindowFlag(Qt.FramelessWindowHint)
print(Countrypage.btn2click)
def countrypage(self):
self.countrywindow = Countrypage()
self.subwindow1.setWidget(self.countrywindow)
self.subwindow1.setWindowTitle("Create Country")
self.subwindow1.setFixedWidth(300)
self.mdi.addSubWindow(self.subwindow1)
self.subwindow1.show()
self.mdi.cascadeSubWindows()
self.countrywindow.closeRequsted.connect(self.subwindow1close)
def subwindow1close(self):
print("close activated from mdi programme")
self.subwindow1.close()
if __name__ == "__main__":
app = QApplication(sys.argv)
mainwindow = MainPage()
app.setStyle("Windows")
mainwindow.show()
sys.exit(app.exec_())
Countrypage.py
import sys,os
from PyQt5.QtWidgets import QWidget,QApplication,QPushButton,QLineEdit,QFormLayout,QVBoxLayout,QHBoxLayout
from PyQt5.QtCore import pyqtSignal
class Countrypage(QWidget):
closeRequsted = pyqtSignal()
def __init__(self):
super().__init__()
self.btn1 = QPushButton("close")
self.btn2 = QPushButton("New")
self.btn1.clicked.connect(self.result)
self.btn2.clicked.connect(self.btn2click)
self.tb_country = QLineEdit()
self.tb_continent =QLineEdit()
self.form_layout = QFormLayout()
self.form_layout.addRow("Country",self.tb_country)
self.form_layout.addRow("continent",self.tb_continent)
self.form_layout.addRow("",self.btn2)
self.form_layout.addRow("",self.btn1)
self.setLayout(self.form_layout)
def result(self):
self.closeRequsted.emit()
def btn2click(self):
btn2text = (self.btn2.text())
print(btn2text)
if __name__=="__main__":
app = QApplication(sys.argv)
countrywin = Countrypage()
countrywin.show()
sys.exit(app.exec_())
The adding and closing of sub-windows is best handled by the main-window. The CountryPage class doesn't need to know anything about the sub-windows. The new/close buttons can be directly connected to methods of the main-window. This makes it easier to manage the sub-windows via the functions of the mdi-area.
Below is a re-write of your example which should do what you asked for:
Main Script:
import sys, os
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
class MainPage(QMainWindow):
def __init__(self):
super().__init__()
self.mdi = QMdiArea()
self.mdi.setFixedSize(1000, 400)
self.mdi.setHorizontalScrollBarPolicy(Qt.ScrollBarAsNeeded)
self.mdi.setVerticalScrollBarPolicy(Qt.ScrollBarAsNeeded)
self.setWindowTitle("Sample Programme")
self.setGeometry(100, 100, 1600, 600)
self.Ui()
def Ui(self):
self.btn1 = QPushButton("Country")
self.btn1.setFixedSize(100, 30)
self.btn1.clicked.connect(self.countrypage)
self.left_layout = QVBoxLayout()
self.right_layout = QHBoxLayout()
self.main_layout = QHBoxLayout()
self.left_layout.setContentsMargins(3, 5, 5, 3)
self.left_layout.addWidget(self.btn1)
self.left_layout.addStretch()
self.right_layout.addWidget(self.mdi)
self.main_layout.setSpacing(5)
self.main_layout.setContentsMargins(0, 0, 0, 0)
self.main_layout.addLayout(self.left_layout)
self.main_layout.addLayout(self.right_layout)
self.main_layout.addStretch()
widget = QWidget()
widget.setLayout(self.main_layout)
self.setCentralWidget(widget)
def countrypage(self):
page = Countrypage()
subwindow = self.mdi.addSubWindow(page)
subwindow.setWindowTitle("Create Country")
subwindow.setFixedWidth(300)
page.btn_close.clicked.connect(self.subwindowclose)
page.btn_new.clicked.connect(self.countrypage)
subwindow.show()
self.mdi.cascadeSubWindows()
def subwindowclose(self):
print("close activated from mdi programme")
current = self.mdi.activeSubWindow()
if current is not None:
self.mdi.activatePreviousSubWindow()
previous = self.mdi.activeSubWindow()
if previous is not None:
previous.widget().update_fields(current.widget())
current.close()
if __name__ == "__main__":
app = QApplication(sys.argv)
mainwindow = MainPage()
app.setStyle("Windows")
mainwindow.show()
sys.exit(app.exec_())
Countrypage.py:
import sys,os
from PyQt5.QtWidgets import QWidget,QApplication,QPushButton,QLineEdit,QFormLayout,QVBoxLayout,QHBoxLayout
from PyQt5.QtCore import pyqtSignal
class Countrypage(QWidget):
def __init__(self):
super().__init__()
self.btn_close = QPushButton("Close")
self.btn_new = QPushButton("New")
self.tb_country = QLineEdit()
self.tb_continent = QLineEdit()
self.form_layout = QFormLayout()
self.form_layout.addRow("Country", self.tb_country)
self.form_layout.addRow("Continent", self.tb_continent)
self.form_layout.addRow("", self.btn_close)
self.form_layout.addRow("", self.btn_new)
self.setLayout(self.form_layout)
def update_fields(self, other):
if isinstance(other, Countrypage):
self.tb_country.setText(other.tb_country.text())
self.tb_continent.setText(other.tb_continent.text())
else:
raise TypeError('invalid page type')
I want to be able to move a layout to another layout based on a user input. I have the following code which does not appear to work for me. If I switch lines 31 and 34 so that they operate on the widget rather than the layout then I get the expected behaviour but I am hoping to operate on all widgets within a layout by just moving the layout.
import sys
from PyQt5.QtWidgets import QPushButton, QWidget, QHBoxLayout, QLabel, QApplication, QVBoxLayout
class b(QWidget):
def __init__(self, name):
super(b, self).__init__()
self.layout = QVBoxLayout(self)
lbl_1 = QLabel(name)
self.layout.addWidget(lbl_1)
class a(QWidget):
def __init__(self):
super(a, self).__init__()
self.layout = QHBoxLayout(self)
self.widget_1 = b('widget 1')
self.widget_2 = b('widget 2')
self.layout.addWidget(self.widget_1)
self.layout.addWidget(self.widget_2)
self.button_layout = QHBoxLayout()
self.move_layout = QPushButton('Move to other layout')
self.move_layout.clicked.connect(lambda: self.move_button())
self.button_layout.addWidget(self.move_layout)
self.widget = 'widget_2'
self.widget_2.layout.addLayout(self.button_layout)
def move_button(self):
if self.widget == 'widget_2':
self.widget_1.layout.addLayout(self.button_layout)
self.widget = 'widget_1'
else:
self.widget_2.layout.addLayout(self.button_layout)
self.widget = 'widget_2'
print('moved widget to {}'.format(self.widget))
if __name__ == '__main__':
app = QApplication(sys.argv)
window = a()
window.show()
sys.exit(app.exec_())
Edit: to clarify, In the example above, the layout I want to move (self.button_layout) is a child layout of self.widget_2.layout. When I click the pushbutton, I want the self.button_layout to be set as a child layout of self.widget_1.layout. Essentially it will do what the code below does but using addLayout instead of addWidget.
import sys
from PyQt5.QtWidgets import QPushButton, QWidget, QHBoxLayout, QLabel, QApplication, QVBoxLayout
class b(QWidget):
def __init__(self, name):
super(b, self).__init__()
self.layout = QVBoxLayout(self)
lbl_1 = QLabel(name)
self.layout.addWidget(lbl_1)
class a(QWidget):
def __init__(self):
super(a, self).__init__()
self.layout = QHBoxLayout(self)
self.widget_1 = b('widget 1')
self.widget_2 = b('widget 2')
self.layout.addWidget(self.widget_1)
self.layout.addWidget(self.widget_2)
self.button_layout = QHBoxLayout()
self.move_layout = QPushButton('Move to other layout')
self.move_layout.clicked.connect(lambda: self.move_button())
self.button_layout.addWidget(self.move_layout)
self.widget = 'widget_2'
self.widget_2.layout.addLayout(self.button_layout)
def move_button(self):
if self.widget == 'widget_2':
self.widget_1.layout.addWidget(self.move_layout)
self.widget = 'widget_1'
else:
self.widget_2.layout.addWidget(self.move_layout)
self.widget = 'widget_2'
print('moved widget to {}'.format(self.widget))
if __name__ == '__main__':
app = QApplication(sys.argv)
window = a()
window.show()
sys.exit(app.exec_())
The problem is that if a layout has a parent then it cannot be changed as the error message indicates:
QLayout::addChildLayout: layout "" already has a parent
One possible solution is to remove the parent:
def move_button(self):
self.button_layout.setParent(None)
if self.widget == "widget_2":
self.widget_1.layout.addLayout(self.button_layout)
self.widget = "widget_1"
else:
self.widget_2.layout.addLayout(self.button_layout)
self.widget = "widget_2"
print("moved widget to {}".format(self.widget))
Another alternative is to place the layout in a QWidget that is the container and that place it in the required layout:
class a(QWidget):
def __init__(self):
super(a, self).__init__()
layout = QHBoxLayout(self)
self.widget_1 = b("widget 1")
self.widget_2 = b("widget 2")
layout.addWidget(self.widget_1)
layout.addWidget(self.widget_2)
self.container = QWidget()
container_layout = QHBoxLayout(self.container)
button = QPushButton("Move to other layout")
button.clicked.connect(self.move_button)
container_layout.addWidget(button)
self.widget = "widget_1"
self.move_button()
def move_button(self):
if self.widget == "widget_2":
self.widget_1.layout.addWidget(self.container)
self.widget = "widget_1"
else:
self.widget_2.layout.addWidget(self.container)
self.widget = "widget_2"
print("moved widget to {}".format(self.widget))
The code below creates an empty dialog when Hello! is pressed:
from PyQt5 import QtWidgets, QtCore
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
w = QtWidgets.QWidget()
layout = QtWidgets.QVBoxLayout()
w.setLayout(layout)
self.setCentralWidget(w)
toyButton = QtWidgets.QPushButton("Hello!")
layout.addWidget(toyButton)
toyButton.clicked.connect(self.showdialog)
def showdialog(self):
d = QtWidgets.QDialog()
d.setWindowTitle("Dialog")
d.setWindowModality(QtCore.Qt.WindowModal)
d.exec_()
if __name__ == '__main__':
app = QtWidgets.QApplication([])
window = MainWindow()
window.show()
app.exec_()
How can I force the dialog to appear within the main window instead of having it floating around as an independent window?
You simply need to give the dialog a parent widget: d = QtWidgets.QDialog(self.centralWidget()). self is also a valid parent; pick your favorite!
You could also add d to the layout: self.centralWidget().layout().addWidget(d);
although this second one does not respect your modality+exec.
Here's the full code comparing both methods:
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
w = QtWidgets.QWidget()
layout = QtWidgets.QVBoxLayout()
w.setLayout(layout)
self.setCentralWidget(w)
toyButton = QtWidgets.QPushButton("Hello!")
layout.addWidget(toyButton)
toyButton.clicked.connect(self.showdialog)
toyButton2 = QtWidgets.QPushButton("Hello2!")
layout.addWidget(toyButton2)
toyButton2.clicked.connect(self.showdialog2)
def showdialog(self):
d = QtWidgets.QDialog(self.centralWidget())
d.setWindowTitle("Dialog")
d.setWindowModality(QtCore.Qt.WindowModal)
d.exec_()
def showdialog2(self):
d = QtWidgets.QDialog()
d.setWindowTitle("Dialog2") # window title won't be seen...
d.setWindowModality(QtCore.Qt.WindowModal)
QtWidgets.QPushButton('Dialog2', parent=d) # ... so we add a little something
self.centralWidget().layout().addWidget(d)
d.exec_()
The project occurs loging in and signing in.
Im trying a transition from registerwindow to mainwindow and when we submit the window is automatically transit to mainwindow. There is only way to do this (at least for me) i have to import two python doc which named mainwindow.py and register.py, they are in same doc by the way.
This is the mainmenu.py
from PyQt5 import QtCore,QtGui,QtWidgets
from window.register import Ui_Form
class Ui_MainWindow(object):
def login(self):
self.window = QtWidgets.QWidget()
self.ui = Ui_Form()
self.ui.setupUi(self.window)
self.window.show()
MainWindow.hide()
and this is register.py
from PyQt5 import QtCore, QtGui, QtWidgets
from window.mainmenu import Ui_MainWindow
import sqlite3
class Ui_Form(object):
def submit(self):
sorgu2 = "Select * From users where nickname = ?"
sorgu = "INSERT INTO users values(?,?)"
self.cursor.execute(sorgu,(self.lineEdit.text(),self.lineEdit.text()))
self.connect.commit()
Form.hide()
self.window2 = QtWidgets.QMainWindow()
self.ui2 = Ui_MainWindow()
self.ui2.setupUi(self.window2)
self.window2.show()
Its supposed to be when i clicked to the button the register window will be hidden and mainmenu window will be show. Same thing for the mainmenu but the direct opposite
I know i am doing circular dependent imports but there is no other way but importing them to each other
If second window will be QDialog then you can hide main window, use exec() for QDialog and main window will wait till you close QDialog, and when it returns to main window then you can show it again.
from PyQt5 import QtWidgets
class MainWindow(QtWidgets.QWidget):
def __init__(self):
super().__init__()
self.button = QtWidgets.QPushButton("Show Second Window", self)
self.button.clicked.connect(self.show_second_window)
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.button)
self.show()
def show_second_window(self):
self.hide() # hide main window
self.second = SecondWindow()
self.second.exec() # will wait till you close second window
self.show() # show main window again
class SecondWindow(QtWidgets.QDialog): # it has to be dialog
def __init__(self):
super().__init__()
self.button = QtWidgets.QPushButton("Close It", self)
self.button.clicked.connect(self.show_second_window)
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.button)
self.show()
def show_second_window(self):
self.close() # go back to main window
app = QtWidgets.QApplication([])
main = MainWindow()
app.exec()
The other popular method is to create two widgets with all contents and replace widgets in one window.
from PyQt5 import QtWidgets
class MainWidget(QtWidgets.QWidget):
def __init__(self, parent):
super().__init__()
self.parent = parent
self.button = QtWidgets.QPushButton("Show Second Window", self)
self.button.clicked.connect(self.show_second_window)
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.button)
self.show()
def show_second_window(self):
self.close()
self.parent.set_content("Second")
class SecondWidget(QtWidgets.QWidget):
def __init__(self, parent):
super().__init__()
self.parent = parent
self.button = QtWidgets.QPushButton("Close It", self)
self.button.clicked.connect(self.show_second_window)
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.button)
self.show()
def show_second_window(self):
self.close()
self.parent.set_content("Main")
class MainWindow(QtWidgets.QWidget):
def __init__(self):
super().__init__()
self.layout = QtWidgets.QVBoxLayout(self)
self.set_content("Main")
self.show()
def set_content(self, new_content):
if new_content == "Main":
self.content = MainWidget(self)
self.layout.addWidget(self.content)
elif new_content == "Second":
self.content = SecondWidget(self)
self.layout.addWidget(self.content)
app = QtWidgets.QApplication([])
main = MainWindow()
app.exec()
EDIT: Change window's content using QStackedLayout
from PyQt5 import QtWidgets
class FirstWidget(QtWidgets.QWidget):
def __init__(self, parent=None):
super().__init__(parent=parent)
layout = QtWidgets.QVBoxLayout(self)
self.button = QtWidgets.QPushButton("Show Second Stack", self)
self.button.clicked.connect(self.change_stack)
layout.addWidget(self.button)
def change_stack(self):
self.parent().stack.setCurrentIndex(1)
class SecondWidget(QtWidgets.QWidget):
def __init__(self, parent=None):
super().__init__(parent=parent)
layout = QtWidgets.QVBoxLayout(self)
self.button = QtWidgets.QPushButton("Show First Stack", self)
self.button.clicked.connect(self.change_stack)
layout.addWidget(self.button)
def change_stack(self):
self.parent().stack.setCurrentIndex(0)
class MainWindow(QtWidgets.QWidget):
def __init__(self):
super().__init__()
self.stack = QtWidgets.QStackedLayout(self)
self.stack1 = FirstWidget(self)
self.stack2 = SecondWidget(self)
self.stack.addWidget(self.stack1)
self.stack.addWidget(self.stack2)
self.show()
app = QtWidgets.QApplication([])
main = MainWindow()
app.exec()
Clicking Dialog_01's button hides its window and opens Dialog_02. Clicking Dialog_02's button should close its windows and unhide Dialog_01. How to achieve it?
import sys, os
from PyQt4 import QtCore, QtGui
class Dialog_02(QtGui.QMainWindow):
def __init__(self):
super(Dialog_02, self).__init__()
myQWidget = QtGui.QWidget()
myBoxLayout = QtGui.QVBoxLayout()
Button_02 = QtGui.QPushButton("Close THIS and Unhide Dialog 01")
Button_02.clicked.connect(self.closeAndReturn)
myBoxLayout.addWidget(Button_02)
myQWidget.setLayout(myBoxLayout)
self.setCentralWidget(myQWidget)
self.setWindowTitle('Dialog 02')
def closeAndReturn(self):
self.close()
class Dialog_01(QtGui.QMainWindow):
def __init__(self):
super(Dialog_01, self).__init__()
myQWidget = QtGui.QWidget()
myBoxLayout = QtGui.QVBoxLayout()
Button_01 = QtGui.QPushButton("Hide THIS and Open Dialog 02")
Button_01.clicked.connect(self.callAnotherQMainWindow)
myBoxLayout.addWidget(Button_01)
myQWidget.setLayout(myBoxLayout)
self.setCentralWidget(myQWidget)
self.setWindowTitle('Dialog 01')
def callAnotherQMainWindow(self):
self.hide()
self.dialog_02 = Dialog_02()
self.dialog_02.show()
self.dialog_02.raise_()
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
dialog_1 = Dialog_01()
dialog_1.show()
sys.exit(app.exec_())
Make the first window a parent of the second window:
class Dialog_02(QtGui.QMainWindow):
def __init__(self, parent):
super(Dialog_02, self).__init__(parent)
# ensure this window gets garbage-collected when closed
self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
...
def closeAndReturn(self):
self.close()
self.parent().show()
class Dialog_01(QtGui.QMainWindow):
...
def callAnotherQMainWindow(self):
self.hide()
self.dialog_02 = Dialog_02(self)
self.dialog_02.show()
If you want the same dialog to be shown each time, do something like:
def callAnotherQMainWindow(self):
self.hide()
if not hassattr(self, 'dialog_02'):
self.dialog_02 = Dialog_02(self)
self.dialog_02.show()
and hide() the child window, rather than closing it.