hey Bay,
Can you post a picture of what your ui looks like right now or share the testtree file too? It’s hard to run the code without it.
Anyway, the easiest thing I can see is that you probably need a widget to apply your button_layout for.
# Line 64
button_widget = QtGui.QWidget()
button_layout = QtGui.QHBoxLayout(button_widget)
# Line 72
self.layout.addWidget(button_layout)
Sorry, correction, my code should be:self.layout.addWidget(button_widget)