How can I use Unity 2d with another window manager besides Metacity?

How can I use Unity 2d with another window manager besides Metacity? (like openbox forexample)

You can add compiz --replace to your startup applications. Restart your session (Log out, and then back in again) and you'll now be using Compiz.

A similar action will be used for openbox. I think it's openbox --replace

To make changes permamnent, You'll have to edit unity session file. Here's short guide for Unity2d and openbox: http://spacecat3000.blogspot.com/2011/11/replace-metacity-with-openbox-in.html

Install openbox:

1. sudo apt-get install openbox
2. Optionally install additional packages (in my case these were installed as dependencies): sudo apt-get install obconf openbox-themes

3. Edit /usr/share/gnome-session/sessions/2d-ubuntu.session file and replace:

   DefaultProvider-windowmanager=metacity with
   
   DefaultProvider-windowmanager=openbox
   

4. Logout, login (with Unity 2d session).
5. Run obconf, choose some nice theme (my was found on box-look.org and changed a little) and configure buttons position.