I'd wager the Windows download is not the full app, rather just an installer. There's no way Qt and PyQt would fit in just 1MB on an OS that doesn't include those as shared libraries.
As a side note: I see the Arch Linux package is 16M, unlike Ubuntu's 39M. Perhaps the app needs a relatively recent Qt or PyQt release that is available from Arch's repos but not on the oldest supported Ubuntu and thus needs to be shipped.
That is correct, the Windows binary is an online installer. The reason for this is that fman uses Google Omaha for its auto-update mechanism [1].
The Arch package is smaller because it declares PyQt as a dependency, rather than shipping it itself. The reason for this is that it was difficult otherwise to make the shipped version of PyQt libraries and dependencies compatible with the ones already on the system.
Yeah, I finally got windows version to download (cut out a few times, HN overload?). The win download is an online installer, so the size makes much more sense. I didn’t check the install directory, but it took 2 minutes to retrieve on slowish WiFi, so I would expect the install size is in-line with the others. (Good point about Arch).
As a side note: I see the Arch Linux package is 16M, unlike Ubuntu's 39M. Perhaps the app needs a relatively recent Qt or PyQt release that is available from Arch's repos but not on the oldest supported Ubuntu and thus needs to be shipped.