Ubuntu 17.10 - what is a default window manager?

Question

I have installed Ubuntu 17.10 which uses Gnome Shell 3.24.2. The following commands:

wmctrl -m

shows an active window manager and I get: Gnome Shell

I have read that Gnome 3 uses Mutter Window Manager, so what is going on ? There is no Mutter process.

Answer 1

GNOME Shell does not use a separate window manager process:

One Process. The first thing to note is that the ideas don’t naturally split into “window manager” and “panel”. The “Activities” view combines showing the windows that are currently open with launchers for existing applications. It would be possible to add complex API’s to the window manager to allow putting extra things into its scene graph. But it is going to be far easier to simply work in a single process with clean internal programming interfaces.

The window manager is still Mutter.

Answer 2

Use:

update-alternatives --display x-window-manager

to find out what wm your Ubuntu is using, or:

ls -l /etc/alternatives/ | grep -i window