Hello,
I play some Windows games through Wine which work fine. For each of them, I create a custom script to set a dedicated prefix and a custom launcher to run said script. They work fine and when adding most of them to Steam Linux as non-steam games, they work fine.

But I've encountered a special case, a software that runs fine from the desktop but not from Steam. I play Deus Ex (GOG version) and the game has to be tweaked a bit to be fully playable on modern computers. One way of doing it easily is to use Kentie's launcher (http://kentie.net/article/dxguide/index.htm) to set high resolution and such. I use it with Wine and it runs perfectly from my desktop. But from Steam, the launcher seems to quit immediately (or it doesn't start at all). I'm not sure why: is it because it's not a fullscreen app? because for some reason Steam can't run a VisualC++ software through Wine?

The bug won't be easy to reproduce as it implies to own Deus Ex (no necessarily the GOG version: the original CD version or the Steam version would work as Kentie's launcher replaces the original executable so you'll just need to have the game data files, you don't need to run Steam Windows through Wine) so I don't really expect a solution but if someone has an idea as to why Steam fails to run this specific case...