pekwm - X11 window manager
The Pekwm Window Manager is written by Claes Nästén. The code is based on the aewm++ window manager, but it has evolved enough that it no longer resembles aewm++ at all. It also has an expanded feature-set, including window grouping (similar to ion, pwm, or fluxbox), auto properties, xinerama and keygrabber that supports keychains, and much more.
For more information visit https://www.pekwm.se/
If you want to install pekwm from source, follow these steps:
git clone https://github.com/pekdon/pekwm.git
cd pekwm
mkdir build && cd build
cmake ..
make
make install
See the Manual for more information on how to use and configure pekwm.
For themes, go to the pekwm themes site that is based on data from the pekwm-theme-index where you can register your own themes for inclusion.