Give Krita a shot. Its UI is much closer to Photoshop than other alternatives, and it's a fully open source project. It's still a bit buggy on Windows but it ru

Give Krita a shot. Its UI is much closer to Photoshop than other alternatives, and it's a fully open source project. It's still a bit buggy on Windows but it runs perfectly on every Linux distro I've tried it on. It's a bit overkill for my needs (I do everything I need with Paint.net/Pinta) but it's worth a look.