The Truth About Mixed-DPI Support in X11

This article clears up the misconceptions surrounding mixed-DPI configuration support in the X11 windowing system. The author delves into the history of X11, from its origins with single X screens, through the Xinerama extension, to the modern XRANDR extension. The article reveals that X11 has always had the capability to support mixed DPI, but the key lies in client applications correctly utilizing the DPI information provided by the XRANDR extension. Different approaches are examined, along with solutions for various scenarios, including using the Qt toolkit for automatic mixed-DPI support and workarounds for toolkits lacking support, such as GTK+. Ultimately, the author calls on developers to improve toolkits and applications to fully leverage X11's mixed-DPI capabilities.