[gtkada] Constraint error using Get_Text, Set_Text or Get_Chars with an GEntry Widget ...

[JJ Escanellas]

I'm trying learn how to copy the text of an Entry Widget to another.
With GLADE I've just created Entry1 and Entry2 in Window1.
I've found that Gtk.GEntry has the Get_Text function and
the Set_Text procedure. So I used them in my project.
But I receive a Constraint Error after execution if I try something like:

window1_pkg.ads:

with Gtk.Window; use Gtk.Window;
with Gtk.Box; use Gtk.Box;
with Gtk.Container; use Gtk.Container;
with Gtk.Label; use Gtk.Label;
with Gtk.Misc; use Gtk.Misc;
with Gtk.GEntry; use Gtk.GEntry;
with Gtk.Button; use Gtk.Button;

package Window1_Pkg is

   type Window1_Record is new Gtk_Window_Record with record
      Hbox1 : Gtk_Hbox;
      Label1 : Gtk_Label;
      Entry1 : Gtk_Entry;
      Entry2 : Gtk_Entry;
   end record;
   type Window1_Access is access all Window1_Record'Class;

   procedure Gtk_New (Window1 : out Window1_Access);
   procedure Initialize (Window1 : access Window1_Record'Class);

   Window1 : Window1_Access;

window1_pkg.adb:

with Gtk.Main;use Gtk.Main;
with Glib;use Glib;
with Gtk.GEntry;use Gtk.GEntry;
with Gtk.Editable;use Gtk.Editable;
with Gtk.Text;use Gtk.Text;
with Ada.Strings.Fixed;use Ada.Strings.Fixed;
with Ada.Strings.Unbounded;use Ada.Strings.Unbounded;
with Ada.Strings.Unbounded.Text_IO;use Ada.Strings.Unbounded.Text_IO;
with Ada.Text_IO;use Ada.Text_IO;

package body Window1_Pkg.Callbacks is

   --------------------------
   --  On_Window1_Destroy  --
   --------------------------

   procedure On_Window1_Destroy
     (Object : access Gtk_Window_Record) is
   begin
          Main_Quit;
   end On_Window1_Destroy;

   -------------------------
  --  On_Entry1_Changed  --
   -------------------------

   procedure On_Entry1_Changed
     (Object : access Gtk_Entry_Record) is
          texto: Unbounded_String;
   begin
          texto := To_Unbounded_String("On_Entry1_Changed...");
          Put_Line(texto);
--        texto := To_Unbounded_String(Get_Text(Window1.Entry1));
          texto := To_Unbounded_String(Get_Chars(Gtk_Editable(Window1.Entry1),Gint( 0 ),Gint( -1 ) ));
          Put_Line(texto);
   end On_Entry1_Changed;

   -------------------------
   --  On_Entry2_Changed  --
   -------------------------

   procedure On_Entry2_Changed
     (Object : access Gtk_Entry_Record) is
          texto: Unbounded_String;
   begin
          Put_Line(texto);

   end On_Entry2_Changed;

end Window1_Pkg.Callbacks;




The constraint error appears when I include Get_Text or Get_Chars or Set_Text in
the code.