`GdkDevicePad` is an interface implemented by devices of type gdk_source_tablet_pad
It allows querying the features provided by the pad device.
Tablet pads may contain one or more groups, each containing a subset of the buttons/rings/strips available. [
[email protected]_n_groups] can be used to obtain the number of groups, [[email protected]_n_features] and [
[email protected]_feature_group] can be combined to find out the number of buttons/rings/strips the device has, and how are they
grouped.
Each of those groups have different modes, which may be used to map each individual pad feature to multiple actions. Only one mode is
effective (current) for each given group, different groups may have different current modes. The number of available modes in a group can
be found out through [[email protected]_group_n_modes], and the current mode for a given group will be notified through events of
type `GDK_PAD_GROUP_MODE`.