I use Infragistic 2010 for this problem.

On a mouse hover, on a custom controller, i set the tooltip text. But the tooltip does not appear.  If I does'nt set a new tooltiptext, the tooltips appear  The ultratooltip is set with a delay so i would'nt use the ShowToolTip.

In the code exemple If the lastOveredDrawable is not equal to drawable, the tooltips will not be appears.  But if the lastOveredDrayable is equal to drawable, it will appears.

 var toolTipInfo = tooltip.GetUltraToolTip(******);
if (RefreshTooltip != null)
{
 var elements = ((MouseHoverEventArgs)e).HoveredElements;
 if (elements != null)
 {
  var drawable = this.GetDrawable(elements);
  if (drawable != null)
  {
   if (drawable != _lastHoveredDrawable)
   {
    tooltip.HideToolTip();
    toolTipInfo.Enabled = Infragistics.Win.DefaultableBoolean.False;
    toolTipInfo.ToolTipText = "test";
   }
   toolTipInfo.Enabled = Infragistics.Win.DefaultableBoolean.True;
   _lastHoveredDrawable = drawable;
  }
  else
  {
   tooltip.HideToolTip();
   toolTipInfo.Enabled = Infragistics.Win.DefaultableBoolean.False;
  }
 }
}
else
{
 tooltip.HideToolTip();
 toolTipInfo.Enabled = Infragistics.Win.DefaultableBoolean.False;
}

Is there a way to update the tooltiptext and show it after with the delay?