+ /**
+ * Computes the outline rectangle of the viewport hit-box.
+ * @param rect the rectangle of the viewport area.
+ * @return Returns the rectangle of the hit-box.
+ * @remarks The default implementation returns an empty hit-box.
+ */
+ virtual QRectF hit_box_rect(const QRectF &rect) const;
+
+ /**
+ * Paints the signal label.
+ * @param p the QPainter to paint into.
+ * @param rect the rectangle of the header area.
+ * @param hover true if the label is being hovered over by the mouse.
+ */
+ virtual void paint_label(QPainter &p, const QRect &rect, bool hover) = 0;
+