I've been trying to make an application using Pyside6 and can't seem to understand why we can't create a QDialog having QTabWidget with just functions. I am not sure if I am making a mistake somewhere so, here is the code I've wrote:

Imports:

from PySide6.QtWidgets import (QMessageBox, QApplication, QWidget, QGridLayout, QLabel, QMainWindow, QTabWidget,QVBoxLayout)
from sys import argv

2 Tabs function:

def WelPage():grid = QGridLayout()wel_tab = QWidget()wel_tab.setLayout(grid)lab_name = QLabel("This is a label")git_link = QLabel("This is a link")git_link.setOpenExternalLinks(True)yt_link = QLabel("Another Link")yt_link.setOpenExternalLinks(True)grid.addWidget(lab_name, 0, 1)grid.addWidget(git_link, 1, 0)grid.addWidget(yt_link, 1, 3)def AboutPage():about_tab = QWidget()lo = QVBoxLayout()purpose = QLabel("A really long label")lo.addWidget(purpose)about_tab.setLayout(lo)

And the main function:

def main():w = QWidget()layout = QVBoxLayout()tw = QTabWidget()w.resize(450, 250)w.setWindowTitle('Window Title')layout.addWidget(tw)tw.addTab(WelPage(), "Welcome Screen")tw.addTab(AboutPage(), "About")tw.show()w.setLayout(layout)w.show()app.exec()if __name__ == "__main__":app = QApplication(argv)main()

Output:

All this does is render a blank Dialog. Not sure why that is. Why must I be forced to use a class rather than this method?

You seem to lack certain basics of how widgets work in Qt.
QWidgets are (generally) supposed to have a parent. So when you instantiate a child widget, you pass to the constructor the parent. This way Qt knows how that they should be displayed. I recommend you follow some tutorials on how to do basic GUIs with Qt in Python.

Then, because you will need to know the parent in the function, either you can use a global variable or pass it as a parameter to the function, like so :

def add_about_widget(parent):about_widget = QWidget(parent)  # <--- here !...

If you want to have menu items, I recommend you use a QMenuBar. Also, Qt nicely create a window for you when you ask it to show() your main widget, but explicitly creating the main window makes things clearer in my opinion.