Two weired lines are shown (Gtk on DirectFB)

[jessonel <jessonel yahoo com>]

Hello,

I'm writing my program with Gtk on DirectFB on ARM9.
  GTK: ver 2.12.10
  DirectFB: ver 1.0.1

My problem is that two black weired lines are shown when do repeat click of button1, 2.
I don't know why this lines are shown as the attached picture.

My code is as below:
=================================================================
#include <stdio.h>
#include <stdlib.h>
#include <gtk/gtk.h> 

GtkWidget *label_num, *label_text;

gboolean on_timer (void *data)
{
 gtk_label_set_text(GTK_LABEL(label_num), "0");
 gtk_label_set_text(GTK_LABEL(label_text), "Hello");
 return true;
}

int main(int argc, char *argv[]) 
{ 
 GtkWidget *window,*fixed,*image,*button;
 GdkColor color = {0, 0x0000, 0x7F00, 0xFF00};

 gtk_init(&argc, &argv); 

 window = gtk_window_new(GTK_WINDOW_TOPLEVEL); 
 gtk_widget_modify_bg (window, GTK_STATE_NORMAL, &color);
 gtk_window_resize(GTK_WINDOW(window), 320, 240); 

 fixed = gtk_fixed_new();
 gtk_container_add(GTK_CONTAINER(window), fixed);

 image = gtk_image_new_from_file("background.png"); // 320x171 black image
 gtk_fixed_put (GTK_FIXED (fixed), image, 0, 45);
 gtk_widget_set_usize(GTK_WIDGET(image), 320, 171);

 image = gtk_image_new_from_file("part1.png");  // 318x70 white image
 gtk_fixed_put (GTK_FIXED (fixed), image, 1, 46);
 gtk_widget_set_usize(GTK_WIDGET(image), 318, 70);

 image = gtk_image_new_from_file("part2.png");  // 310x91 black image
 gtk_fixed_put (GTK_FIXED (fixed), image, 5, 122);
 gtk_widget_set_usize(GTK_WIDGET(image), 310, 91);

 label_num = gtk_label_new("0");
 gtk_fixed_put (GTK_FIXED (fixed), label_num, 15, 65);
 gtk_widget_set_usize(GTK_WIDGET(label_num), 101, 44);

 label_text = gtk_label_new("Hello");
 gtk_fixed_put (GTK_FIXED (fixed), label_text, 119, 80);
 gtk_widget_set_usize(GTK_WIDGET(label_text), 73, 22);

 button = gtk_button_new_with_label("Button1");
 gtk_fixed_put (GTK_FIXED (fixed), button, 9, 125);
 gtk_widget_set_usize(GTK_WIDGET(button), 97, 84);

 button = gtk_button_new_with_label("Button2");
 gtk_fixed_put (GTK_FIXED (fixed), button, 214, 125);
 gtk_widget_set_usize(GTK_WIDGET(button), 97, 84);

 gtk_widget_show_all(window); 

 g_timeout_add (500, (GSourceFunc)on_timer, (gpointer) 0);

 gtk_main(); 
 return 0; 
} 
===================================================================

Anybody help me!

Jess