XmTextScroll man page
XmTextScroll — A Text function that scrolls text
#include <Xm/Text.h> void XmTextScroll( Widget widget, int lines);
XmTextScroll scrolls text by a given number of lines in a Text widget. The sign of the number is interpreted according to the value of the XmNlayoutDirection resource.
Specifies the Text widget ID
Specifies the number of lines of text to scroll. A positive value causes text to scroll upward; a negative value causes text to scroll downward. Note that the text will scroll only as long as one line of text remains visible in the window.
If a navigator exists, this function uses the XmQTnavigator trait to update the vertical navigator's value.
In the case of vertical writing, a positive value causes the text to scroll forward; a negative value causes the lines to scroll backward.
For a complete definition of Text and its associated resources, see XmText(3).