Description: Restore a saved area of the graphics screen
Mapped Command: RESTORE GRAPHICS SCREEN
FUNCTION __RestGScreen(label)
   local Pos1a, Pos1b, Pos2a, Pos2b, Handle
   local screen := __ScanScreens(label)
   if screen > 0
      Pos1a  := _screens_[screen,1]           // upper left row
      Pos1b  := _screens_[screen,2]           // upper left column
      Pos2a  := _screens_[screen,3]           // upper left row
      Pos2b  := _screens_[screen,4]           // upper left column
      handle := _screens_[screen,5]           // dGE handle
      if handle != 0
         snappaste(__XdGE(Pos1b),__YdGE(Pos2a),handle)
         snapkill(handle)
         _screens_[screen,1] := NullInteger   // upper left row
         _screens_[screen,2] := NullInteger   // upper left column
         _screens_[screen,3] := NullInteger   // lower right row
         _screens_[screen,4] := NullInteger   // lower right column
         _screens_[screen,5] := NullInteger   // dGE handle
         _screens_[screen,6] := NullString    // GL memvar
      else
         __HandleError(NoHandlesLeft,screen)
      endif
   else
      __HandleError(NoSuchHandle,label)
   endif
RETURN(Void)