I'm adding a QLineEdit to the menu bar with setCornerWidget. However, when setting a size with either setFixedWidth or setMinimumWidth, the QLineEdit is clipping through the window:
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
menu = self.menuBar()
search = QLineEdit(self)
search.setFixedWidth(200)
menu.setCornerWidget(search)

It seems to be a bug, a workaround is to use a QWidget as a container: