There doesn\'t seem to be a .Show() kind of method for the Windows.Control.ToolTip, incl in ToolTipService.
Finally i ended with this .. and it's working fantastic ..
Popup myPopup = new Popup();
myPopup.PlacementTarget = control; //FrameworkElement where you want to show this tooltip
myPopup.Placement = PlacementMode.Top;
myPopup.PopupAnimation = PopupAnimation.Slide;
myPopup.AllowsTransparency = true;
TextBlock popupText = new TextBlock();
popupText.Text = ErrorMessage; //Message you want to show
popupText.Background = Brushes.AliceBlue;
popupText.Foreground = Brushes.Red;
//popupText.FontSize = 12;
popupText.TextWrapping = TextWrapping.Wrap;
myPopup.Child = popupText;
// popup1.CustomPopupPlacementCallback =
// new CustomPopupPlacementCallback(placePopup);
//myPopup.HorizontalOffset = control.ActualWidth - popupText.ActualWidth;
control.ToolTip = myPopup;
myPopup.IsOpen = true;
myPopup.StaysOpen = false;