void phtog(int flag = 1)
{
//  This is an auxiliary macro giving functions to the very
//  small buttons in phgeom. If flag = 1, toggle between black
//  and white screen; if flag = 2, toggle default (filling 3d
//  view) vs. undistorted (same x, y, z scale) views; if flag
//  = 3, toggle normal view vs. 2x scale (enlarges rotator box too).
//  The toggles bw, fv and x2 are defined in the calling program
//  so they will not be reinitialized. Several variables are
//  defined in the calling macro (scoped inward).   DMcL 1/Sep/97
//
//      These procedural subroutines are brought into CINT via
//  .L and are separately coded because of the error message
//  "Limitation: Can not define body of function in temp file..."
//  one gets from CINT if an in-line C routine or C++ class is
//  attempted.  There seems to be little documentation on this.

  c1->cd();
// Screen color toggle
  if (flag == 1)
  {
    if (bw == 0) c1->SetFillColor(1);
    if (bw == 1) c1->SetFillColor(10);
    if (bw == 2) c1->SetFillColor(132);
    if (++bw >= 3) bw = 0;
  }

// View undistorted toggle
  if (flag == 2)
//   min[3], mins[3], max[3], maxs[3] defined in caller
  {
    Float_t rmin = 0.0;
    Float_t rmax = 0.0;
    int i;
    TView *view = c1->GetTView();
    if (fv)
    {
       fv = 0;
       view->SetRange(mins,maxs);
    }
    else
    {
       fv = 1;
       view->GetRange(min,max);
       for (i = 0; i < 3; i++)
       {
          mins[i] = min[i];
          maxs[i] = max[i];
          if (rmin > min[i]) rmin = min[i];
          if (rmax < max[i]) rmax = max[i];       
       };
       for (i = 0; i < 3; i++)
       {
          min[i] = rmin;
          max[i] = rmax;
       };
       view->SetRange(min,max);
    }
  }

// Double view size toggle
  if (flag == 3)
  {
    if (x2)
    {
       x2 = 0;
       c1->Range(-1.0,-1.0,1.0,1.0);
    }
    else
    {
       x2 = 1;
       c1->Range(-0.5,-0.5,0.5,0.5);
    }
  }

  c1->Draw();
  c1->Update();
}