How to set a textbox to be a print object

[Jeff Donkersgoed]

When using Excel 2003, you can right click a textbox, and set it to be a
print object. I'm not sure how to do this in Excel 2007, but my main problem
is to find out how to set this in code? I have the following, but
chart.Shapes.Item(z).ControlFormat.PrintObject is already set to true before
I explicitly set it, so I don't think it's the right spot. I can't see the
text boxes in the print preview in 2003 (but can in 2007).

chart = ((Excel.ChartObject)wsClientPatient.ChartObjects(1)).Chart;
for (int z = 1; z <= chart.Shapes.Count; z++)
{
chart.Shapes.Item(z).ControlFormat.PrintObject = true;
}