Please try this code with SP2 both in XP and Vista.
I can't see the tooltips any more.
Can you confirm?
It would be very sad.

Public myForm

myForm = CreateObject("TempForm")
myForm.Show()

**************************************************
*-- ParentClass:  form
*-- BaseClass:    form
*-- Time Stamp:   10/13/07 12:06:09 PM
*
DEFINE CLASS TempForm AS form


DoCreate = .T.
ShowTips = .T.
Caption = "Form1"
Name = "Form1"

ADD OBJECT grid1 AS grid 


PROCEDURE Init

WITH Thisform.Grid1
	.ColumnCount = 2
	.RecordSource = "myCursor"
	.Name = "Grid1"
	.Column1.ControlSource = "myCursor.Code"
.Column1.ToolTipText = "This column tooltip shows with SP1, doesn't with SP2"
	.Column1.Name = "Column1"
	.Column2.ControlSource = "myCursor.Descr"
	.Column2.Name = "Column2"

.column1.header1.ToolTipText = "This header tooltip shows with SP1, doesn't with SP2"

Endwith

ENDPROC



PROCEDURE Load
	Create Cursor myCursor (Code C(10), Descr C(200))
	Insert Into myCursor Values ("abc","This text shows as tooltip since it is not completely shown in the column")
ENDPROC


ENDDEFINE
*
*-- EndDefine: TempForm
**************************************************