I have a few widgets such as a QLabel and QPushbuttons hovering over a VTK scene like below. As you can see, when I add a border-radius to the them, the remaining area around the labels or buttons is black. I would instead like to see the VTK scene behind them. How can I achieve this?

I have a few widgets such as a QLabel and QPushbuttons hovering over a VTK scene like below. As you can see, when I add a border-radius to the them, the remaining area around the labels or buttons is black. I would instead like to see the VTK scene behind them. How can I achieve this?

I am using PyQT5 and VTK for displaying information, and have been using observers to register mouse click events through the interactor style. For some reason, when multiple buttons are clicked, the release event gets lost. I have modified one of the VTK QT examples to do this: