Hi
Thank you for additional information. I managed to reproduce the problem on my side. you will be notified as soon as it is fixed.
It seems the problem occurs because FitShapeToText option is ignored. As a workaround you can specify height of the text box. Please try using the following code:
newTextBox.Width = 80;
newTextBox.Height = 40;
Best regards.
Alexey Noskov
Developer/Technical Support
Aspose Auckland Team