VDisplaySaveScreenImage - displays the 3DVIEWNIX screen image.
  VDisplaySaveScreenImage(scrn_file, frame, xloc, yloc)
  char *scrn_file;
  int frame;
  int xloc, yloc;
  VDisplaySaveScreenImage displays a 3DVIEWNIX screen image.
VDisplaySaveScreenImage reads the specified frames of the screen image and
displays it in the image window at the location specified.
VDisplaySaveScreenImage also installs the colormap and updates the COLOR.COM 
file with the values associated with the frame to be displayed. The screen 
file contains the number of frames in the first four bytes, followed by the 
image frame, the number of colormap entries, and the colormap contents. 
Retrun Value
  0 - work successfully.
  1 - memory allocation error.
  2 - read error.
  4 - file open error.
  209 - invalid frame number in the screen file.
  240 - frame outside the image window boundary.
  scrn_file - specifies the name of the file to be displayed.
  frame - specifies the frame number to be displayed.
  xloc, yloc - specifies x and y coordinates of the upper left corner of the
        rectangle, relative to the origin of the image window.
Side Effects
Entry Conditions
  If xloc, or yloc is not valid, or scrn_file is NULL, or VCreateColormap
not called earlier, VDisplaySaveScreenImage prints an error message to the
standard error stream. produces a core dump file and exits from the current
Related Functions
VEraseSaveScreenCommand, VGetSaveScreenSwitchValue, VGetSaveScreenFilename, VCheckEventsInButtonWindow, VDisplaySaveScreenCommand, VOutputSaveScreenImage.