an class='period'>.</span><span class='id identifier rubyid_left_edge'>left_edge</span><span class='period'>.</span><span class='id identifier rubyid_w'>w</span> <span class='op'>+</span> <span class='lparen'>(</span><span class='id identifier rubyid_upper_left_corner'>upper_left_corner</span><span class='period'>.</span><span class='id identifier rubyid_w'>w</span> <span class='op'>-</span> <span class='ivar'>@header</span><span class='period'>.</span><span class='id identifier rubyid_x'>x</span><span clas