Strange code in xterm.c

[Eli Zaretskii <eliz@gnu.org>]

This a large part of the body of x_check_fullscreen:

      int width = FRAME_COLS (f), height = FRAME_LINES (f);
      struct x_display_info *dpyinfo = FRAME_X_DISPLAY_INFO (f);

      switch (f->want_fullscreen)
        {
          /* No difference between these two when there is no WM */
        case FULLSCREEN_BOTH:
        case FULLSCREEN_MAXIMIZED:
          width = x_display_pixel_width (dpyinfo);
          height = x_display_pixel_height (dpyinfo);
          break;
        case FULLSCREEN_WIDTH:
          width = x_display_pixel_width (dpyinfo);
          break;
        case FULLSCREEN_HEIGHT:
          height = x_display_pixel_height (dpyinfo);
        }

      if (FRAME_COLS (f) != width || FRAME_LINES (f) != height)
        {
          change_frame_size (f, height, width, 0, 1, 0);
          SET_FRAME_GARBAGED (f);
          cancel_mouse_face (f);
        }

Am I missing something, or does it mix up display dimensions in pixels
and in character units?