fine.
Perhaps the zIndex property should be included in the documentation.

like this:
   $('#prompt').tooltip({
            position: 'top',
            content: $('#promptContent').html(),
            onShow: function () {
                $(this).tooltip('tip').css({
                    zIndex:99999     // I want it to be top of all
                });
               //  $(this).tooltip("reposition");  //when uncomment this line, the z-index value is undefined. the tooltip is covered by other elememts which have big z-index.
            }
        });

I found a solution：

    function centerOverall(target, offset) {
        let jq = $(target);
        let opts = jq.data('window').options;
        let offsetTop = opts.top - (window.parent.innerHeight -  window.innerHeight) / 2 + ((offset && offset.y) ? offset.y : 0);
        let offsetLeft = opts.left - (window.parent.innerWidth -  window.innerWidth) / 2 + ((offset && offset.x) ? offset.x : 0);
        if (offsetTop < 0) offsetTop = 0;
        if (offsetLeft < 0) offsetLeft = 0;
        jq.window("move", { top: offsetTop, left: offsetLeft });
    }
    //extend easyui window
    $.extend($.fn.window.methods, {
        centerOverall: function (jq, offset) {
            return jq.each(function () {
                centerOverall(this, offset);
            });
        },
    });

I use layout in my project and almost all pages are shown in center region with iframe,  when window,dialog or messager are shown in pages, they are centered to the page window , but not the browser window.  I don't want to realize it by setting top/left or moving every time the window or dialog are open.  Allthough parent.$.messager can  be a good method for messagers, but I don't want its modal property applying to whole window.
How can I easily realize it?

ok. wonderful idea.

 Applying  datebox to <input type='date' />  can not completely override built-in appearance, how to fix it?

OK. thanks.

I use custom buttons in datagrid, it works fine when changing page by pager's navigator, but when I try to reload data from server side through $('#dg').datagrid({ queryParams:{}}), buttons disappear.
Is it a bug? or how to make it always show ?

It works fine. Thanks.

     When I drag and drop text from the same page into a textbox，it works，but when I  drag and drop text from other application(e.g., MS Word) into a textbox，the textbox can not hold the value which shows in gray color and disapears when focus is got.
   Is it a bug? How to fix it?

When I use cell editing datagrid, GetChanges() returns the rows that I just click in but make no changes. I find that it only occurs when data contains numbers. For instance, the original data is {qty:10},  it becomes {qty:'10'} after editing.