Improve documentation

gtk/gtkaccessiblerange.c

@@ -32,6 +32,10 @@
  * In addition to this interface, its implementors are expected to provide the
  * correct values for the following properties: %GTK_ACCESSIBLE_PROPERTY_VALUE_MAX,
  * %GTK_ACCESSIBLE_PROPERTY_VALUE_MIN and %GTK_ACCESSIBLE_PROPERTY_VALUE_NOW.
+ * 
+ * For controls where a minimum increment makes no sense and which do not allow
+ * setting the current value from the user, the default implementation of this
+ * interface suffices.
  */
 
 #include "config.h"

gtk/gtkaccessiblerange.h

@@ -37,7 +37,24 @@ struct _GtkAccessibleRangeInterface
 {
   GTypeInterface g_iface;
 
+  /**
+   * GtkAccessibleRangeInterface::get_minimum_increment:
+   * @self: a `GtkAccessibleRange`
+   * 
+   * Returns the minimum increment for this `GtkAccessibleRange`.
+   * The default implementation returns 0.0, which indicates that a minimum
+   * increment does not make sense for this implementation.
+   * @returns: the minimum increment
+   */
   double (* get_minimum_increment) (GtkAccessibleRange *self);
+  /**
+   * GtkAccessibleRangeInterface::set_current_value:
+   * @self: a `GtkAccessibleRange`
+   * @value: the value to set
+   * 
+   * Sets the current value of @self to @value.
+   * This operation should behave similarly as if the user performed the action.
+   */
   void (* set_current_value) (GtkAccessibleRange *self, double value);
 };