* button area.
* The exact behavior of the touchpad is implementation-dependent.
*
+ * Top software button area
+ * ========================
+ * On selected touchpads, the top area of the touchpad is a separate set of
+ * software buttons split into a left, middle and right button area.
+ * Pressing the touchpad down with a finger in those areas will generate
+ * clicks as shown in the diagram below:
+ *
+ * @code
+ +------------------------+
+ | LEFT | MIDDLE | RIGHT |
+ +------------------------+
+ | |
+ | LEFT |
+ | |
+ +------------------------+
+ | LEFT | RIGHT |
+ +------------------------+
+ * @endcode
+ * This behavior is enabled on the Lenovo *40 series (T440, T540, T240...)
+ * and the Lenovo Helix, Yoga S1 and Carbon X1 2nd.
+ *
* Clickfinger
* ===========
* On Apple touchpads, no button areas are provided. Instead, use a