Setting default name of an image using the GTK file chooser

gtk_save_file_dialog.c

static void open_export(GApplication *app, gpointer user_data) {

    GtkWidget *dialog;
    gint res;

    dialog = gtk_file_chooser_dialog_new (
        "Save Texture (.png)",
        GTK_WINDOW(user_data),
        GTK_FILE_CHOOSER_ACTION_SAVE,
        "Cancel",
        GTK_RESPONSE_CANCEL,
        "Save",
        GTK_RESPONSE_ACCEPT,
        NULL
    );

    // Problem start: filename and folder are not set

    gtk_file_chooser_set_do_overwrite_confirmation (GTK_FILE_CHOOSER(dialog), TRUE);
    gtk_file_chooser_set_current_folder(GTK_FILE_CHOOSER(dialog), "~/Pictures");
    gtk_file_chooser_set_filename (GTK_FILE_CHOOSER(dialog), "texture.png");
    res = gtk_dialog_run (GTK_DIALOG (dialog));

    // Problem end

    if(res == GTK_RESPONSE_ACCEPT) {

        char *filename;
        filename = gtk_file_chooser_get_filename (GTK_FILE_CHOOSER(dialog));
        g_print("The user selected filename: %s\n", filename);
        g_free (filename);

    }

    gtk_widget_destroy (dialog);
}