libmutter-2-dev 3.28.1-1ubuntu1 (i386 binary) in ubuntu cosmic

 Mutter is a small window manager, using GTK+ and Clutter to do
 everything.
 .
 Mutter is the clutter-based evolution of Metacity, which, as the
 author says, is a "Boring window manager for the adult in you. Many
 window managers are like Marshmallow Froot Loops; Metacity is like
 Cheerios."
 .
 This package contains the development files.