Python qt: windows

In Qt, any widget can be a window, simply by calling one of it's methods show() or raise_().

Despite this, there are 2x classes that are built to be used primarilly as windows:

• QtWidgets.QMainWindow()
• QtWidgets.QDialog()

Modal vs Modeless

In UI terms, a Modal window is a window that interrupts the flow of execution, stealing the focus, and disallowing other windows from being interacted with until it is dismissed. Modal windows are displayed using the method raise_()

A Modeless window is a normal window. You can start as many windows as you'd like, and you can use modeless windows alongside each other. Modeless windows are displayed using the method show().

The two windows can be used together, but a modal window can only launch new modal windows.

Window Widgets

QWidget

QWidgets (any QWidget subclass) can be a window. Even if you have no production use-case for this, you'll find it invaluable for testing.

wid = QtWidgets.QPushButton('A Button')
wid.show()

QMainWindow

QMainWindows are a special type of widget that is intended to be used as a top-level window. All of the features of a QMainWindow can be reproduced in a QWidget, it exists solely for convenience. QMainWindows have builtin support for:

• menubar (file menu)
• toolbars (for actions - like photoshop)
• docking widgets (top, left, right, bottom)
• statusbar (mouseover notifications)

win = QtWidgets.QMainWindow()
wid = QtWidgets.QLabel('Example Main Widget')

win.setCentralWidget(wid)
win.show()

QDialog

QDialogs can be used like any other widget, but their intended purpose is for modal prompts that can be accepted/rejected. MessageBoxes, for example are QDialogs.

win = QtCore.QDialog()
action = win.exec_()

if action is QtWidgets.QDialog.Accepted:
    # do something
elif action is QtWidgets.QDialog.Rejected:
    # do something else

QMessageBox

msgbox = QMessageBox()

msgbox.setText("The document has been modified.")                                   ## Main Text
msgbox.setInformativeText("Do you want to save your changes?")                      ## Smaller SubText
msgbox.setStandardButtons(QMessageBox.Save|QMessageBox.Discard|QMessageBox.Cancel)  ## Buttons to display
msgbox.setDefaultButton(QMessageBox.Save)
action = msgBox.exec_()

if msgbox.buttonRole(msgbox.clickedButton()) is QtWidgets.QMessageBox.ButtonRole.RejectRole:
    # do something

## Getting info from QMessageBox
if   action == QMessageBox.Save:
    # do something
elif action == QMessageBox.Discard:
    # do something
elif action == QMessageBox.Cancel:
    # do something

Useful Methods

widget.window()                                          # get any widget's window (or None if is window)

window.setAttribute(PySide.QtCore.Qt.WA_DeleteOnClose)   # delete this window from memory on close
window.resize(600, 300)
window.setWindowTitle('My Window')