GtkEntry set width issue

static void
event_box_pressed_cb (GtkWidget *widget, GdkEvent *event, gpointer user_data)
{
    GtkWidget *popover;
    GtkWidget *radio1;
    GtkWidget *radio2;
    GtkWidget *radio3;
    GtkWidget *radio4;
    GtkWidget *frame;
    GtkWidget *grid;
    GtkWidget *entry;

    entry = gtk_entry_new ();
    grid = gtk_grid_new ();
    popover = gtk_popover_new (widget);
    radio1 = gtk_radio_button_new_with_label (NULL, "128");
    radio2 = gtk_radio_button_new_with_label_from_widget (GTK_RADIO_BUTTON (radio1), "256");
    radio3 = gtk_radio_button_new_with_label_from_widget (GTK_RADIO_BUTTON (radio1), "512");
    radio4 = gtk_radio_button_new_with_label_from_widget (GTK_RADIO_BUTTON (radio1), "1024");
    frame = gtk_frame_new ("Choose");

    gtk_grid_attach (GTK_GRID (grid), entry, 0, 0, 1, 1);
    gtk_grid_attach (GTK_GRID (grid), radio1, 0, 1, 1, 1);
    gtk_grid_attach (GTK_GRID (grid), radio2, 0, 2, 1, 1);
    gtk_grid_attach (GTK_GRID (grid), radio3, 0, 3, 1, 1);
    gtk_grid_attach (GTK_GRID (grid), radio4, 0, 4, 1, 1);
    //gtk_container_add (GTK_CONTAINER (frame), grid);
    gtk_container_add (GTK_CONTAINER (popover), grid);

    gtk_entry_set_width_chars (GTK_ENTRY (entry), 10);
    gtk_widget_set_margin_start (entry, 4);
    gtk_widget_set_margin_end (entry, 4);
    gtk_widget_set_margin_start (radio1, 4);
    gtk_widget_set_margin_start (radio2, 4);
    gtk_widget_set_margin_start (radio3, 4);
    gtk_widget_set_margin_start (radio4, 4);

    g_signal_connect (radio1, "toggled", G_CALLBACK (radio_button_cb), entry);
    g_signal_connect (radio2, "toggled", G_CALLBACK (radio_button_cb), entry);
    g_signal_connect (radio3, "toggled", G_CALLBACK (radio_button_cb), entry);
    g_signal_connect (radio4, "toggled", G_CALLBACK (radio_button_cb), entry);

    gtk_widget_show_all (popover);
}