Different computed dataPageSize for same listGrid

[Blama]

Hi Isomorphic,

this is about the 2nd issue here.

Please see this two testcases in this sample (v10.1p_2017-08-09):
Original:

isc.ListGrid.create({
    ID:"dsListGrid",
    width: "100%",
    height: "100%",
    minFieldWidth:80,
    autoFetchData: true,
    dataSource: "supplyItem"
});

Modified:

isc.ListGrid.create({
    ID:"dsListGrid",
    width: "100%",
    height: "100%",
    minFieldWidth:80,
    autoFetchData: true,
    dataSource: "supplyItem",
    sortField: "SKU",
    groupByField: "category",
    sortByGroupFirst: true
});

For me (Win 10, Chromium 60, no zoom, FullHD) the request for the unmodified sample is for startRow:0, endRow:87. The one for the modified sample, after the ListGrid recognized that it can't group, is for startRow:0, endRow:75.
As the browser size and ListGrid-real estate is the same in both cases, I'd expect the dataPageSize to be the same as well.
As reference: For me, in the 2nd (sorted) ListGrid the last fully visible row (without scrolling/on load) is "SKU 11314900" (=28 data rows). I also can see that the endRow differs in the 1st case if I make the browser window smaller. So perhaps, for the 2nd request after unsuccessful grouping, the dataPageSize is just set to its default value.

Obviously, this is a very minor issue.

Best regards
Blama