There are numerous other GUI toolkits available. The prominent examples are GTK+ and KDE. The new Wayland server is intended as a replacement for the X server. The approach to integrate these toolkits is always the same: you need to find a way to process the GUI toolkit events with the vibe.d event manager. As vibe.d utilizes the widely used
libevent library, you may get lucky and somebody may have already provided a solution. Alternatively, you can look for a
libev solution. To use
libev with vibe.d, you need to specify the
libev configuration in your
subConfigurations "vibe-d" "libev"
In case you have to roll your own implementation, you should take a look at
libasync. This event loop library is written in D and the source is available on GitHub at https://github.com/etcimon/libasync. You can clone this repository and use it as a base for your integration task.