For scenario 2-4, the workaround would be utilizing the OnSelectRow to re-select the previously selected row, in addition to re-populate the new row (scenario 4).

In both scenario 2 and 3, during OnBeforeUpdate client side event handler you will need to buffer the row key value and using the buffered row key value in the OnRowSelect event handler you will need to reselect the previous row. Here is the snippet:

var selectLastRow = null;

function WebGrid1_OnBeforeUpdate(controlId, tblName, rowObject)
{
    var grid = ISGetObject(controlId);
    var retVal = false;

    //Line of code to determine return value
    
    if(!retVal)
        selectLastRow = rowObject.KeyValue;

    return retVal;
}

function WebGrid1_OnRowSelect(ctrlId)
{
    var grid = ISGetObject(ctrlId);

    if (selectLastRow != null)
    {
        var rowKey = selectLastRow;
        selectLastRow = null;

        setTimeout(function()
        {
            grid.ClearSelection();
            grid.RootTable.GetRowByKeyValue(rowKey).Select();
            
            grid.RootTable.GetRowByKeyValue(rowKey).GetCell("CustomerID").ActivateEdit();

            grid.RootTable.GetRowByKeyValue(rowKey).SetDataChanged();
            grid.MarkEdit();
        }, 15);
    }
}

For scenario 4, it will be similar with the scenario 2 and 3 however, in this scenario you will be utilizing the OnBeforeAdd event handler:

var newRowTemp = null;

function WebGrid1_OnBeforeAdd(controlId, tblName, rowObject)
{
    var grid = ISGetObject(controlId);

    var retVal = false;
    
    //Determine the return value             
    
    if(!retVal)
        newRowTemp = rowObject.GetCells();

    return retVal;
}

function fillNewRow(newRowTempCells)
{
    var grid = ISGetObject("WebGrid1");

    setTimeout(function()
    {
        var newRowObj = grid.GetRowByElement(grid.RootTable.GetNewRow());

        grid.ClearSelection();

        newRowObj.Select();
        newRowObj.BeginEdit();

        var newRowCells = newRowObj.GetCells();

        for (var i = 0; i < newRowCells.length; i++)
        {
            newRowCells[i].SetText(newRowTempCells[i].Text);
            newRowCells[i].SetValue(newRowTempCells[i].Value);

            if (i == 0)
                newRowCells[0].ActivateEdit();
        }

        newRowObj.SetDataChanged();
        grid.MarkEdit();
    }, 15);
}

function WebGrid1_OnRowSelect(ctrlId)
{
    var grid = ISGetObject(ctrlId);

    if (newRowTemp != null)
    {
        var rowKeyCells = newRowTemp;
        newRowTemp = null;

        fillNewRow(rowKeyCells);
    }
}

For scenario 4, in order for the WebGrid to always trigger the OnBeforeAdd event handler you will need to use the NewRowLostFocusAction="AlwaysUpdate" attribute under WebGrid LayoutSettings

Setting the event end time to 00.00 is known as swith day event in WebScheduler and it will be rendered in all day event section.

Regarding your scenario, you will need to modify the shipped editing form to accept HH:mm:ss format instead of the HH:mm format or you will need to create a custom editing form that will allow you to set the end time to 23:59:59.

We have provided some article regarding custom editing form in article "EditingForm" in WebScheduler documentation or in the blog.

Currently our developer is focusing on WebUI Studio 2010 release. At the earliest a fix will be available by the end of May 2010.

For your second scenario, you will need to use WebCombo.NET set additional filter function, as described in "How-to: Filter the data in WebCombo using SetAdditionalFilter method" WebCombo documentation. In WebGrid, the function should be invoked during OnEnterEditMode client side event handler. Here is the snippet:

function wgTest_OnEnterEditMode(controlId, tblName, editObject)
{
	var wgTest = ISGetObject(controlId);

	if (editObject.type == "WebComboNET")
	{
	    editObject.element.SetAdditionalFilters("[Type] = '" + editObject.ToCellObject().Value + "'");
	}

	return true;
}

Attached is a simple sample of the scenario you are describing. I could not replicate the issue using the sample in my environment. The test is done using all the latest build of WebGrid and WebDesktop.

Feel free to modify the sample so the issue could be replicated.