XtTranslateCoords - translate widget coordinates
#include <X11/Intrinsic.h>
void XtTranslateCoords(Widget w, Position x,
    Position y, Position *rootx_return, Position
    *rooty_return);
  - rootx_return
- 
    
 
- rooty_return
- Returns the root-relative x and y coordinates.
- x
- 
    
 
- y
- Specify the widget-relative x and y coordinates.
- w
- Specifies the widget.
While XtTranslateCoords is similar to the Xlib
  XTranslateCoordinates function, it does not generate a server request
  because all the required information already is in the widget's data
  structures.
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface