Gtk Print Probleem

[ldries46]

I have a problem with printing from Gtk.

The print is working correctly if I print a document which results in 19
pages. But with one page with 48 lines of text I just get an empty page and
I just don't get the print dialog. Herewith I give you the part of the
program where it goes wrong.:

In the On_Print procedure:

last_line := integer(nr) - 1;
Print_Op := new Gtkada_Print_Operation_Record;
Gtkada.Printing.Initialize (Print_Op);
Gtk_New(Print_Set);
Set_Current_Page (Print_Op, 1);
Number := long_float(last_line) / long_float(delta_lines);
Number := long_float'Rounding(Number + 0.4999999);
nr_Pages := Gint(Number);
Set_N_Pages (Print_Op, nr_Pages);
Set_Use_Full_Page(Print_Op, true);
Set_Unit (Print_Op, points);
Print_Op.Set_Print_Settings(Print_Set);
--------------------------------------------------------------------
-- procedure On_Draw_Page
-- (Self : not null access Gtk_Print_Operation_Record;
-- Call : Cb_Gtk_Print_Operation_Gtk_Print_Context_Gint_Void;
-- After : Boolean := False);
--------------------------------------------------------------------
On_Draw_Page(Print_Op, Draw);
Result := Connect_and_Run(Print_Op ,Action_Print_Dialog, Main_Window);

Draw is declared as

Draw : Cb_Gtk_Print_Operation_Gtk_Print_Context_Gint_Void
:= Draw_Page'Access;


and the Draw_Page procedure

procedure Draw_Page
(Op : access Gtk_Print_Operation_Record'Class;
Context : not null access Gtk_Print_Context_Record'Class;
Page_Number : Gint) is
Cr : Cairo_Context;
nr : integer;
width : integer;
rb : boolean;
-- re : boolean;
ok : boolean;
str : Unbounded_String;
begin
nr := first_line;
Cr := Get_Cairo_Context (Context);
Set_Source_Rgb (Cr, 0.0, 0.0, 0.0);
Select_font_face(Cr, "Monospace", CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_NORMAL);
Set_Font_Size(Cr, GDouble(9));
if nr = 1 then
pagenr := 1;
else
pagenr := pagenr + 1;
end if;
if pagenr rem 2 = 1 then
width := 70;
else
width := 40;
end if;
if last_page_line > last_line then
last_page_line := last_line;
end if;
ok := false;
while not ok loop
Get_Iter_At_Line(Main_Window.Draw_Buffer, first, Gint(nr));
Get_Iter_At_Line_Offset(Main_Window.Draw_Buffer, endln, Gint(nr),
500);
move_to(cr, Gdouble(width), Gdouble((nr - first_line + 1) * 13 +
65));
str :=
To_Unbounded_String(Get_Text(Main_Window.Draw_Buffer,first,endln));
show_text(cr, To_String(str));
nr := nr + 1;
ok := nr >= last_page_line;
if nr <= last_line then
Forward_Line(first, rb);
end if;
end loop;
first_line := nr - 1;
last_page_line := last_page_line + delta_lines;
end Draw_Page;