I just bought the game today on Steam. When I first launched it it was version 1.23 and it still is right now. But something happened the second time I launched it (I had quit the game and closed Steam itself, then re-started Steam and re-launched the game), that second launch had a “download process” blue bar on-screen before the main menu appeared, and then I was automatically sent back to the Desktop with the official GSB patch 1.24 installer screen open. It wanted to install the update under the default retail (or perhaps I should say non-Steam) installation path, namely under the usual Program Files folder (followed by the game name, etc).
Instead I refused to update and canceled it because I think that Steam games need specific updates and they aren’t usually compatible with official updates from installers like all non-Steam patches are. I wanted to point at this to the GSB team, that they perhaps should be aware that the Steam version tries to update like the non-Steam version and that it might not be a good thing to do. At least even if I refused to update I was still able to launch the game afterwards and it remained version 1.23. So I thought that posting this might help the team figure out about a way to update the Steam version properly. If in fact it was alright and I could have updated then please let me know.