Iterates over widget children to change checkboxes stylesheet.

    The default rendering of checkboxes does not allow to tell a focused one
    from an unfocused one.

def style_checkboxes(widget):
    """
    Iterates over widget children to change checkboxes stylesheet.

    The default rendering of checkboxes does not allow to tell a focused one
    from an unfocused one.
    """

    ww = widget.findChildren(QCheckBox)
    for w in ww:
        w.setStyleSheet("QCheckBox:focus {border: 1px solid #000000;}")