Qt Compositor's goal is to be "a tool box which is being used as a base layer for other people when they are going to write their own custom Wayland compositors."
Additionally, "Qt-Compositor abstracts away all communication needed by a Wayland compositor. Hence the primary task for someone who implements a custom compositor is how the surfaces will be drawn. On the client side, the display information is sent over the protocol, and is available to all clients through the usual Qt-APIs."
Sounds interesting for the promising Wayland Display Server project.