Maximum canvas% scroll-range of 1,000,000 pixels?

I see the following contract violation in my program when the scroll range exceeds 1,000,000. I'm providing pixels as the units to the set-scroll-range function. Assuming using pixels is correct here, I propose 1,000,000 pixels is too small for a maximum range since I have run into the limit displaying a text file with about 30,000 lines.

set-scroll-range in canvas%: contract violation
expected: (integer-in 0 1000000)
given: 1130504.0
Context (plain; to see better errortrace context, re-run with C-u prefix):
/usr/local/racket/share/pkgs/gui-lib/mred/private/lock.rkt:43:38
/usr/local/racket/collects/ffi/unsafe/atomic.rkt:73:13
/home/jonathan/git/molasses/src/test/newcanvas.rkt:265:4 update-scrollbars
/usr/local/racket/collects/racket/private/more-scheme.rkt:148:2 call-with-break-parameterization
/usr/local/racket/share/pkgs/gui-lib/mred/private/lock.rkt:43:38
/usr/local/racket/collects/ffi/unsafe/atomic.rkt:73:13
/usr/local/racket/share/pkgs/gui-lib/mred/private/wx/common/queue.rkt:435:6
/usr/local/racket/share/pkgs/gui-lib/mred/private/wx/common/queue.rkt:460:2 yield

Start with the canvas% set-scroll-range entry point and reproduce the reported value from src/test/newcanvas.rkt in update-scrollbars. Check how the 1,000,000 contract limit relates to pixel units and scrollbar behavior. Done means the supported range is clarified and the reported over-limit case has an appropriate, tested outcome.