Use the ScrollToolTip property to specify whether the control displays a tooltip when the user clicks and moves the scrollbar's thumb. By default, the ScrollToolTip property is empty. If the ScrollToolTip property is empty, the tooltip is not shown when the user clicks and moves the thumb of the scroll bar. The OffsetChanged event notifies your application that the user changes the scroll position. Use the SortPartVisible property to specify the parts being visible in the control's scroll bar. 

The following VB sample displays a tooltip when the user clicks and moves the thumb in the control's scroll bar:

Private Sub ComboBox1_OffsetChanged(ByVal Horizontal As Boolean, ByVal NewVal As Long)
    If (Not Horizontal) Then
        ComboBox1.ScrollToolTip(exVScroll) = "Record " & NewVal
    End If
End Sub

The following VB.NET sample displays a tooltip when the user clicks and moves the thumb in the control's scroll bar:

Private Sub AxComboBox1_OffsetChanged(ByVal sender As System.Object, ByVal e As AxEXCOMBOBOXLib._IComboBoxEvents_OffsetChangedEvent) Handles AxComboBox1.OffsetChanged
    If (Not e.horizontal) Then
        AxComboBox1.set_ScrollToolTip(EXCOMBOBOXLib.ScrollBarEnum.exVScroll, "Record " & e.newVal.ToString())
    End If
End Sub

The following C++ sample displays a tooltip when the user clicks and moves the thumb in the control's scroll bar:

void OnOffsetChangedComboBox1(BOOL Horizontal, long NewVal) 
{
	if ( !Horizontal )
	{
		CString strFormat;
		strFormat.Format( _T("%i"), NewVal );
		m_comboBox.SetScrollToolTip( 0, strFormat );
	}
}

The following C# sample displays a tooltip when the user clicks and moves the thumb in the control's scroll bar:

private void axComboBox1_OffsetChanged(object sender, AxEXCOMBOBOXLib._IComboBoxEvents_OffsetChangedEvent e)
{
    if ( !e.horizontal )
        axComboBox1.set_ScrollToolTip(EXCOMBOBOXLib.ScrollBarEnum.exVScroll, "Record " + e.newVal.ToString());
}

The following VFP sample displays a tooltip when the user clicks and moves the thumb in the control's scroll bar:

*** ActiveX Control Event ***
LPARAMETERS horizontal, newval

If (1 # horizontal) Then
    thisform.ComboBox1.ScrollToolTip(0) = "Record " + ltrim(str(newval))
EndIf