T830-003: Disable scrolling event for Spin button preferences

In some case, the user will scroll the list of pref and unwantedly
change a Spin button value => there is no feedback and this is
troublesome to debug/detect.
This patch prevents such cases.

Change-Id: I906ad9c4cd9ef0c18a38eb2aa98d1dc05ae0d7ea

kernel/src/default_preferences.adb

@@ -28,6 +28,7 @@ with XML_Utils;                  use XML_Utils;
 with Default_Preferences.GUI;    use Default_Preferences.GUI;
 with Dialog_Utils;
 
+with Gdk.Event;                  use Gdk.Event;
 with Gtk.Adjustment;             use Gtk.Adjustment;
 with Gtk.Box;                    use Gtk.Box;
 with Gtk.Button;                 use Gtk.Button;
@@ -2160,6 +2161,8 @@ package body Default_Preferences is
                Page_Increment => 10.0);
       Gtk_New (Spin, Adj, 1.0, The_Digits => 0);
       Spin.Set_Editable (True);
+      --  Disable the incrementation by scrolling
+      Spin.Set_Events (Spin.Get_Events and not Scroll_Mask);
 
       Preference_Handlers.Connect
         (Adj, Gtk.Adjustment.Signal_Value_Changed, Gint_Changed'Access, P);

widgets/src/switches_chooser-gtkada.adb

@@ -16,6 +16,7 @@
 ------------------------------------------------------------------------------
 
 with Ada.Strings.Unbounded;  use Ada.Strings.Unbounded;
+with Gdk.Event;              use Gdk.Event;
 with Glib;                   use Glib;
 with Glib.Object;            use Glib.Object;
 with Gtk.Adjustment;         use Gtk.Adjustment;
@@ -533,6 +534,9 @@ package body Switches_Chooser.Gtkada is
             Set_Tooltip (Editor, Spin, Switch, S);
             Pack_Start (Hbox, Spin, True, True, 0);
 
+            --  Disable the incrementation by scrolling
+            Spin.Set_Events (Spin.Get_Events and not Scroll_Mask);
+
             User_Widget_Callback.Connect
               (Spin, Gtk.Spin_Button.Signal_Value_Changed,
                On_Spin_Changed'Access,