I'm using SDL2 at the base of my own engine to help with cross platform compatibility at the lowest level. We're also using it at work for Z Steel Soldiers (and other games) and we had numerous reports of strange things happening which all sounded like DPI scaling issues to me.
On some machines our games would launch and appear to be clipped off-screen. So you'd only see the top left portion of the screen and couldn't select any buttons or elements that were off screen. The other issue was that the full screen would render, but the mouse would be trapped in the top left portion.
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