Use a MouseDown or MouseUp event procedure to specify actions that will occur when a mouse button is pressed or released. Unlike the Click and DblClick events, MouseDown and MouseUp events lets you distinguish between the left, right, and middle mouse buttons. You can also write code for mouse-keyboard combinations that use the SHIFT, CTRL, and ALT keyboard modifiers. Use the ItemFromPoint property to determine the cell or the item over the cursor. Use the Change event to notify your application that user clicks an item or presses the ENTER key. Use the SelectionChange event  to notify your application that a new item is selected. Use the CellImages property to assign multiple icons to a cell.

The following VB sample displays the index of the icon being clicked in a cell:

Private Sub ComboBox1_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    Dim i As HITEM, h As HitTestInfoEnum, c As Long
    With ComboBox1
        i = .ItemFromPoint(X / Screen.TwipsPerPixelX, Y / Screen.TwipsPerPixelY, c, h)
    End With
    If (i <> 0) Or (c <> 0) Then
        If exHTCellIcon = (h And exHTCellIcon) Then
            Debug.Print "The index of icon being clicked is: " & (h And &HFFFF0000) / 65536
        End If
    End If
End Sub

The following C++ sample displays the index of the icon being clicked in a cell:

void OnMouseUpCombobox1(short Button, short Shift, long X, long Y) 
{
	long c = 0, hit = 0, i = m_combobox.GetItemFromPoint( X, Y, &c, &hit );
	if ( i != 0 )
		if ( 68 /*exHTCellIcon*/ == (hit & 68 /*exHTCellIcon*/ ) )
		{
			CString strOutput = V2S( &m_combobox.GetItems().GetCellCaption(COleVariant(i), COleVariant(c) ) );
			strOutput += " Index = ";
			strOutput += V2S(COleVariant(hit >> 16));
			strOutput += "\r\n";
			OutputDebugString( strOutput );
		}
}

The following VB.NET sample displays the cell from the cursor:

Private Sub AxComboBox1_MouseUpEvent(ByVal sender As Object, ByVal e As AxEXCOMBOBOXLib._IComboBoxEvents_MouseUpEvent) Handles AxComboBox1.MouseUpEvent
    With AxComboBox1
        Dim i As Integer, c As Integer, hit As EXCOMBOBOXLib.HitTestInfoEnum
        i = .get_ItemFromPoint(e.x, e.y, c, hit)
        If (i >= 0) Then
            If (hit And EXCOMBOBOXLib.HitTestInfoEnum.exHTCellIcon) = EXCOMBOBOXLib.HitTestInfoEnum.exHTCellIcon Then
                Debug.WriteLine(.Items.CellCaption(i, c) & " Index = " & ((hit And &HFFFF0000) / 65536))
            End If
        End If
    End With
End Sub

The following C# sample displays the cell from the cursor:

private void axComboBox1_MouseUpEvent(object sender, AxEXCOMBOBOXLib._IComboBoxEvents_MouseUpEvent e)
{
	EXCOMBOBOXLib.HitTestInfoEnum hit;
	int c = 0, i = axComboBox1.get_ItemFromPoint(e.x, e.y, out c, out hit);
	if (i != 0)
		System.Diagnostics.Debug.WriteLine(axComboBox1.Items.get_CellCaption(i, c).ToString() + " Index = " + (Convert.ToUInt32(hit) >> 16).ToString());
}

The following VFP sample displays the cell from the cursor:

*** ActiveX Control Event ***
LPARAMETERS button, shift, x, y

local c, hit
c = 0
hit = 0
with thisform.ComboBox1
	.Items.DefaultItem = .ItemFromPoint( x, y, @c, @hit )
	if ( .Items.DefaultItem <> 0 )
		if ( bitand( hit, 68 )= 68 )
			wait window nowait .Items.CellCaption( 0, c ) + " Index=" + Str( Int((hit - 68)/65536) )
		endif
	endif
endwith