[gtkmm] ScaleButton: Document the constructors.

[Murray Cumming <murrayc src gnome org>]

commit 6c583871eac217d48077fdebacb50750d8c5de6a
Author: Murray Cumming <murrayc murrayc com>
Date:   Sun Dec 7 20:03:58 2014 +0100

    ScaleButton: Document the constructors.

 gtk/src/scalebutton.hg |   18 +++++++++++++++++-
 1 files changed, 17 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/scalebutton.hg b/gtk/src/scalebutton.hg
index 659b2ce..695fb10 100644
--- a/gtk/src/scalebutton.hg
+++ b/gtk/src/scalebutton.hg
@@ -47,11 +47,27 @@ class ScaleButton
   _IMPLEMENTS_INTERFACE(Orientable)
 
 public:
-  //We custom-implement the constructor because gtk_scale_button_new() does more than just call 
g_object_new():
+  //We custom-implement the constructor because gtk_scale_button_new() does more than just call 
g_object_new().
+  /** Creates a GtkScaleButton, with a range between min and max , with a stepping of step.
+   *
+   * @param size A stock icon size.
+   * @param min The minimum value of the scale (usually 0).
+   * @param max The maximum value of the scale (usually 100).
+   * @param step The stepping of value when a scroll-wheel event, or up/down arrow event occurs (usually 2).
+   */
   explicit ScaleButton(IconSize size, double min, double max, double step, const std::vector<Glib::ustring>& 
icons);
   _IGNORE(gtk_scale_button_new)
 
   //We add the constructor without icons because the C functions allows that to be NULL.
+  /** Creates a GtkScaleButton, with a range between min and max , with a stepping of step.
+   *
+   * @param size A stock icon size.
+   * @param min The minimum value of the scale (usually 0).
+   * @param max The maximum value of the scale (usually 100).
+   * @param step The stepping of value when a scroll-wheel event, or up/down arrow event occurs (usually 2).
+   *
+   * @newin{3,16}
+   */
   explicit ScaleButton(IconSize size, double min, double max, double step);
 
 #m4 _CONVERSION(`const std::vector<Glib::ustring>&',`const 
gchar**',`Glib::ArrayHandler<Glib::ustring>::vector_to_array($3).data ()')