XmTextXYToPos — A Text function that accesses the character position nearest an x and y position

XmTextXYToPos accesses the character position nearest to the specified x and y position, relative to  the
       upper left corner of the Text widget.

       In  the case of horizontal writing, the position is the origin of the character.  In the case of vertical
       writing, the position is the vertical origin of the character.

       widget    Specifies the Text widget ID

       x         Specifies the x position, relative to the upper left corner of the widget

       y         Specifies the y position, relative to the upper left corner of the widget

       For a complete definition of Text and its associated resources, see XmText(3).

XmTextXYToPos  —  A  Text  function  that  accesses  the  character  position nearest an x and y position
       "XmTextXYToPos" "Text functions" "XmTextXYToPos"

XmText(3).

                                                                                                XmTextXYToPos(3)

       Returns the character position in the text nearest the x and y position specified.  This  is  an  integer
       number of characters from the beginning of the buffer. The first character position is 0 (zero).

       #include <Xm/Text.h>
       XmTextPositionXmTextXYToPos(
       Widgetwidget,
       Positionx,
       Positiony);