My understanding after talking to support is that a grid with a popup editor has code behind the scenes that stops adverse scrolling behavior when the popup window closes.  However, under certain circumstances, this doesn't work if you have a grid nested in your popup editor that also has a popup editor.  As it was described to me, this "behavior is not directly related to the Grid, but the Kendo Window. Generally, it provides the preventScroll property, but I am afraid this scenario is more complex due to the window being internally embedded into the Grid".

The exact scenario I found was that if you shrink you browser window small enough that you need to use some scrolling, scroll down your grid a little, then do something to cause the popup editor to open.  Scroll down again to get to your nested grid, open that popup editor, then close it.  The browser then auto scrolls to the top.

I was given this code to fix the issue (and it DOES fix it):

<script>
    kendo.ui.Grid.fn._destroyEditableOrg = kendo.ui.Grid.fn._destroyEditable;
    kendo.ui.Grid.fn._destroyEditable = function () {
        var that = this;
        if (that._editContainer) {
            var kw = that._editContainer.data().kendoWindow;
            kw.setOptions({
                modal: false
            });
        }
        that._destroyEditableOrg();
    };
</script>

The problem is that these fields aren't documented... I would never have figured this out on my own.  So my feature request is that either this behavior is fixed or these properties exposed from the Grid settings.  

-Steven

PS: For Telerik, the original ticket was 1589389.