GtkComboBox移出屏幕

如何解决GtkComboBox移出屏幕

我在屏幕顶部有GtkComboBox。当选择第一项，一切正常，但是当我选择第二或第三项，行1和2消失在屏幕上方。有没有办法使GtkComboBox始终向下弹出？ （默认是所选项目在中间）。还是有其他解决方案？

我正在使用weston-wayland 5.0的gtk版本3.22.3。

代码如下：

#include <gtk/gtk.h>

int main( int argc,char *argv[])
{
    gtk_init(&argc,&argv);

    GtkWidget* window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_fullscreen (window);
    
    GtkWidget* vBox = gtk_Box_new (GTK_ORIENTATION_VERTICAL,0);

    GtkWidget* labelSelector = gtk_combo_Box_text_new();
    gtk_combo_Box_text_append_text (labelSelector,"first text");
    gtk_combo_Box_text_append_text (labelSelector,"second text");
    gtk_combo_Box_text_append_text (labelSelector,"third text");
    gtk_combo_Box_set_active(labelSelector,0);
    gtk_Box_pack_start(vBox,labelSelector,0);

    GtkWidget* button = gtk_button_new_from_icon_name("media-playback start",GTK_ICON_SIZE_DND);
    gtk_Box_pack_start(vBox,button,1,0);


    gtk_container_add(GTK_CONTAINER(window),vBox);

    gtk_widget_show_all (window);

    gtk_main();

    return 0;
}