is an integer data type that holds a characters position within
a text string for
Text and TextField.
An XmTextPosition value conceptually points to the gap
between two characters.
For example, consider a text string consisting of N characters.
A value of 0 refers to the position immediately prior to the first character.
A value of 1 refers to the position in between the first and second characters.
A value of N refers to the position immediately following the last
character. Therefore, the text string of N characters
actually contains N + 1 positions.