Try content_width = <horz pixels in your image> and snap mode=full_snap. As long as your windows (OS level) scaling is not anything different to 100%, then it should scale the title image perfectly.
Tried that. No difference. Snap doesn't snap. Never has. Title screen image still scales up and down when you move the separator between the editing panel and the playing panel or when playing in windowed mode and you resize the window.
