I recommend QToolButton class. The class is intended for toolbars but it is a fully functional "bitmap button" which can display a QIcon without a text. Therefore, 2 QPushButtons with 3 QToolButtons in between and QPixmap (or QImage) to the right. If you click Up or Down, redo the icons. When you click a QToolButton, redo the image.

As to devising the GUI: set sizes of the button and the QIcon, remove text and set style to QToolButtonIconOnly in the Designer.