function reflow(&$parent, &$context)
 {
     // Check if there are any boxes in parent's line box
     if ($parent->line_box_empty()) {
         // The very first whitespace in the line box should not affect neither height nor baseline of the line box;
         // because following boxes can be smaller that assumed whitespace height
         // Example: <br>[whitespace]<img height="2" width="2"><br>; whitespace can overextend this line
         $this->width = 0;
         $this->height = 0;
     } elseif (is_a($parent->last_in_line(), "WhitespaceBox")) {
         // Duplicate whitespace boxes should not offset further content and affect the line box length
         $this->width = 0;
         $this->height = 0;
     } elseif ($this->maybe_line_break($parent, $context)) {
         $this->width = 0;
         $this->height = 0;
     }
     parent::reflow($parent, $context);
 }