C++

aewm++
antiX IceWM Desktop
Asteroid Launcher
Batocera EmulationStation
Blackbox
Caelestia Shell
Common Desktop Environment (CDE)
Compiz
Deepin Desktop Environment (DDE)
Denial
doWM
Fluxbox
FLWM
Glacier UX
herbstluftwm
Hyprland
IceWM
KDE Plasma
Kodi Standalone Session
KWin
Lingmo Desktop
Liri Shell
Lomiri
Lumina Desktop
LXQt
MATE
Maui Shell
MaXX Interactive Desktop
mir_demo_server
mir_x11_kiosk
miracle-wm
miral-kiosk
miral-system-compositor
miwm
MX Linux Fluxbox Desktop
newm
Noctalia
Orbitiny Desktop
Page
pekwm
Plasma Mobile
Plasma Nano
poloWM
Puppy JWM/ROX Desktop
Qvwm
Raspberry Pi Desktop
RetroArch Lakka Session
Sapphire
Sommelier
Tiley
Tiny Core FLWM Desktop
Treeland
TreeWM
Trinity Desktop Environment (TDE)
TWin (Trinity Window Manager)
Ubuntu Frame
UKUI
Unity 7
Wayfire
Wayfire Shell (wf-shell)
Westeros
Win8DE
wm2
wmx
WSLg RAIL Shell
Xiri WM