§ ¶Implementing per-monitor DPI awareness

Windows 8.1 will soon offer the ability to use different DPI scaling settings for different monitors. This is a cool feature, but one that will need some fixup in existing programs, particularly since the virtualization method that scales up existing programs looks rather ugly. Below is a dump of everything I've encountered while implementing per-monitor DPI awareness in an existing program.

Fair warning: this is based on the publicly available Windows 8.1 Preview (build 9431), so behaviors may change in the final (RTM) release.