The syntax for XmTextSetLayoutModifier() is:
#include <Xm/Xm.h>XmString XmStringDirectionCreate(direction)XmStringDirection direction
XmStringDirectionCreate creates a compound string with a single component, a direction with the given value. On the other hand, the XmNlayoutDirection resource sets a default rendering direction for any compound string (XmString) that does not have a component specifying the direction for that string. Therefore, to set the layout direction, you set the appropriate value for the XmNlayoutDirection resource. You need not create compound strings with specific direction components.
When the application renders an XmString, the application should check whether the string was created with an explicit direction (XmStringDirection). If the application was provided no direction component, the application should check the value of the XmNlayoutDirection resource for the current widget and use that value as the default rendering direction for the XmString.