I have noticed my mouse has a tendency to not stay locked to the game window when playing Battle.net games through Lutris. Sometimes the mouse stays confined to the window, but it’s about 50-50 whether it will. I do use 2 monitors, so I suspect that’s the issue, but the fact it’s not reliable. It’s mainly a problem with Starcraft 2 or HotS. I tried to look through the Wine settings, but I have no idea what I would even be looking for…
If you press the little arrow next to the wine icon next to Play, you should get a button “Wine configuration”. Then, go to “Graphics” in the top bar, and enable “Automatically capture the mouse in full-screen windows” (or disable it, if you want it off.).
It is odd that it wouldn’t be consistent, though. Lemme know if it works!