Based on my test using the latest nightly build the issue has been fixed, the fix will be release in the next hotfix release.

rowObject.RowElement.setAttribute("CustomRowColor", "customrowcolor");

function WebGrid1_OnAfterExitEditMode(controlId, tableName, editObject) {
    var grid = ISGetObject(controlId);
    var selObj = grid.GetSelectedObject();
    var row = selObj.ToRowObject();
    var rowCells = row.GetCells();

    var columnLength = grid.RootTable.Columns.length;
    var rowObject = row;

    var rowElement = rowObject.RowElement;

    if (rowElement != null && rowElement.getAttribute("CustomRowColor") == "customrowcolor") {
        for (var i = 1; i <= columnLength; i++) {
            var cell = rowElement.cells[i];
            if (cell != null) { cell.style.setAttribute("backgroundColor", "Red", true); }
        }
    }
}

Using the latest ClientUI, ClientUI 4, commanding has run without any issue in WPF.

FYI, the GridPresenter has not fully support MVVM. However, it seems this issue is caused by a bug. A bug report has been submitted so the developer could analyze the issue further.

Using the technique discussed in this article, I have create a simple sample of WebCombo and PageStatePersister. In my simple sample, after postback which invoke the save viewstate method the WebCombo still have the data. Attached is the simple sample I created to test this issue.

Do you mind providing a simple runnable sample of your issue so we could analyse the issue further?