I am working on a combobox with PyQt. I am expecting to have round corners on the dropdown. Here is what it looks like now:

As it shows, there is a white corner with 0 radius on the bottom right. What is confusing is that when I place the window on top of a black background, the extra would “go away” or maybe it is just black:

I tried it with other colors and it is hard to tell what color that corner would turn into:

Does anyone know what might be the cause of that extra corner, or how to remove it?

Here is my code:

        self.label = QLabel("smething")

        self.combobox = QComboBox()
        self.combobox.addItems(["1","2","3","4"])

        vbox = QVBoxLayout(self)
        vbox.addWidget(self.label)
        vbox.addWidget(self.combobox)

        widget = QWidget(self)
        widget.setLayout(vbox)

        self.resize(200,100)
        widget.resize(200,100)

        self.combobox.view().window().setWindowFlags(Qt.Popup | Qt.FramelessWindowHint)
        self.combobox.view().window().setAttribute(Qt.WA_TranslucentBackground)

        self.setStyleSheet("""
            QComboBox {
                background-color: black;
                color: #00ff00;
                selection-background-color: transparent;
                border: 1.5px solid #00ff00;  /* Border color and thickness */
                border-radius: 5px;        /* Rounded corners of the button */
                padding: 5px;
            }
            QComboBox editable {
                background-color : yellow;
            }
            QComboBox QAbstractItemView {
                color: #00ff00;   /* Text color of the drop-down items */
                background-color: red;  /* Optional: Set background color of the drop-down list */
                border: 1.5px solid #00ff00;  /* Border of the drop-down list */
                border-radius: 10px;  /* Rounded corners for the drop-down list */
                selection-background-color: #00ff00;
                selection-color: red;
                padding: 5px;
            }
        """)