Adding jqGrid Custom Navigation to Top Toolbar
OK, it seems that I found a way which looks like better. The idea is to use navButtonAdd with the "#list_toppager_left" instead of "#pager".
I modified the old answer so, that one custom button are added on the top of the navigation toolbar together with one standard button. Other elements from the top navigation toolbar will be removed. The results will looks like
You can see the corresponding demo live here.