[gtkmm] Gtk::Widget: Document drag_dest_set(Gtk::DestDefaults, Gdk::DragAction)

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 83358ea4cc24be8d026b97192917d2b7fff4d6f2
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Wed Dec 27 09:14:03 2017 +0100

    Gtk::Widget: Document drag_dest_set(Gtk::DestDefaults, Gdk::DragAction)

 gtk/src/widget.hg |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/widget.hg b/gtk/src/widget.hg
index 7f3c980..2f21ef3 100644
--- a/gtk/src/widget.hg
+++ b/gtk/src/widget.hg
@@ -407,7 +407,18 @@ public:
   _WRAP_METHOD(void drag_highlight(), gtk_drag_highlight)
   _WRAP_METHOD(void drag_unhighlight(), gtk_drag_unhighlight)
 
-  //TODO: Change the defaults? Maybe we should use ALL for DestDefaults. See other drag_dest_set() methods 
here and in other widgets.
+  /** Sets a widget as a potential drop destination, and adds default behaviors.
+   *
+   * This %drag_dest_set() overload, with its default values of @a flags and
+   * @a actions, is useful if you provide your own signal handlers for
+   * signal_drag_motion() and signal_drag_drop() and let the signal handlers
+   * decide if a drop is possible.
+   *
+   * @see drag_dest_set(const Glib::RefPtr<Gdk::ContentFormats>&, DestDefaults, Gdk::DragAction)
+   *
+   * @param flags Which types of default drag behavior to use.
+   * @param actions A bitmask of possible actions for a drop onto this widget.
+   */
   void drag_dest_set(DestDefaults flags = DestDefaults(0), Gdk::DragAction actions = Gdk::DragAction(0));
 
   // I've used Gdk::DragAction::COPY as the default, because Gdk::DragAction::DEFAULT means that