inconsistent line width from draw-line on Windows

I am using Racket 8.2. The width of line with odd y is larger. The backing scale reported by dc is 1.5.

#lang racket
(require racket/gui/base)

(define f (new frame% [label "test"] [width 320] [height 240]))
(define c (new (class canvas%
                 (inherit get-dc)
                 (super-new)

                 (define/override (on-paint)
                   (define dc (get-dc))
                   (send dc draw-line 10 10 100 10)
                   (send dc draw-line 10 21 100 21)))
               [parent f]))

(send f show #t)

Setting smoothing mode to 'aligned could alleviate this problem.

Start with the provided Racket GUI example and the canvas on-paint entry point, then reproduce the two draw-line calls on Windows with a backing scale of 1.5. The issue is done when equivalent horizontal lines have consistent widths without relying on smoothing mode 'aligned.