[gtkmm] Gtk::SpinButton: Make a constructor explicit and add documentation

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 0fbffbbf1f6b042e6085eaec08b91f247e39d219
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Mon Jul 10 16:04:36 2017 +0200

    Gtk::SpinButton: Make a constructor explicit and add documentation

 gtk/src/spinbutton.hg |   22 +++++++++++++---------
 1 files changed, 13 insertions(+), 9 deletions(-)
---
diff --git a/gtk/src/spinbutton.hg b/gtk/src/spinbutton.hg
index 803c506..2cc75cf 100644
--- a/gtk/src/spinbutton.hg
+++ b/gtk/src/spinbutton.hg
@@ -30,10 +30,10 @@ _WRAP_ENUM(SpinType, GtkSpinType)
 
 class Adjustment;
 
-/** numeric Entry with up/down buttons
+/** Numeric Entry with up/down buttons.
  * Slightly misnamed, this should be called a SpinEntry.
  *
- * The SpinButton widget looks like this:
+ * The %SpinButton widget looks like this:
  * @image html spinbutton1.png
  *
  * @ingroup Widgets
@@ -44,12 +44,17 @@ class SpinButton : public Entry
 public:
   _WRAP_ENUM(UpdatePolicy, GtkSpinButtonUpdatePolicy)
 
-  //TODO: This constructor should be implicit
-  //: create instance
-  // adjustment: see Gtk::Adjustment
-  // climb_rate:
-  // digits: number of decimal digits (has to be < 6)
-  SpinButton(double climb_rate = 0.0, guint digits = 0);
+  /** Creates a %SpinButton.
+   * @param climb_rate The acceleration rate when you hold down a button.
+   * @param digits The number of decimal places to display.
+   */
+  explicit SpinButton(double climb_rate = 0.0, guint digits = 0);
+
+  /** Creates a %SpinButton.
+   * @param adjustment The Adjustment object that this spin button should use.
+   * @param climb_rate The acceleration rate when you hold down a button.
+   * @param digits The number of decimal places to display.
+   */
   _WRAP_CTOR(SpinButton(const Glib::RefPtr<Adjustment>& adjustment, double climb_rate = 0.0, guint digits = 
0), gtk_spin_button_new)
 
 
@@ -115,4 +120,3 @@ public:
 };
 
 } // namespace Gtk
-