This property specifies the default primary text direction. For
the details of each value, please refer to XTextStyle.Direction.
The value of this property is not saved to the PDF file and it
exists purely to determine the way that appearances are generated
for annotations containing text.
If you are using Hebrew or Arabic you may wish to set this value
to left-to-right to provide support to bi-directional text and
In general you will not want to set the primary direction to
right-to-left as this is something that Acrobat does not support
and may result in field changes when, in Acrobat, you click into a
field to edit the text.