OpenEuphoria

One for the C fans. Translating this bit of C code:

#define INVERT_Y(_y) (height-y) 
 
static int motion_cb(Ihandle *ih,int x,int y,char* status) 
{ 
  (void)status; 
 
  if (move) 
  { 
    double dif_x, dif_y; 
    int height = IupGetInt2(ih, "RASTERSIZE"); 
 
    dif_x = x - pos_x; 
    dif_y = y - pos_y; 
 
    pos_x = x; 
    pos_y = y; 
 
    gluUnProject(pos_x, INVERT_Y(pos_y), 0.0,... 

Should I really just replace INVERT_Y(pos_y) with (height-y)?
Is the use of pos_y a complete red herring?

Also, while I'm here, is (void)status; just a way of suppressing unused errors/warnings?

Pete