Some of them I publish and release, but so many people are only interested in "newer" stuff that it often isn't worth the time.
I rarely offer patches back upstream. Mostly because they wouldn't accept them, gutting build systems, ripping out features is not the direction that these projects go. Hence the article on "bloat" I suppose ;)
Some of my work to replace the Gtk in GtkRadiant with FLTK got upstreamed in FLTK itself though (Fl_Flex): https://github.com/fltk/fltk/blob/master/FL/Fl_Flex.H
I only really care about Windows 7 and OpenBSD platforms. Linux tends to build due to the simplification of the software but I only get the urge to give it a shot once in a blue moon. Part of my work on Half-Life was to *remove* Android support because I find it a mess and was damaging the codebase.