QVBoxLayout: How to vertically align widgets to the top instead of the center

If you have a QVBoxLayout and want your fixed size widgets to be stacked at the top, you can simply append a vertical stretch at the end:

layout.addStretch()

If you have multiple stretchers or other stretch items, you can specify an integer stretch factor argument that defines their size ratio.

See also addStretch and addSpacerItem.

Add two layout.addStretch() before and after adding the widgets to center them vertically:

    layout.addStretch()
    layout.addWidget(self.message)
    layout.addWidget(self.userid_field)
    layout.addWidget(self.password_field)
    layout.addWidget(self.loginButton)
    layout.addStretch()

Not sure whether this answers your original question, but it is the answer to the one that I had when googling and being led to this page – so it might be useful for others too.