Actual Window Manager Here

But have you ever stopped to ask: what is an actual window manager?

Notice a pattern: the window manager is never just a manager. It is a compositor, an input router, a focus policy arbiter, and often a renderer for window borders and decorations. The pure, Platonic "window manager"—a module that only manages rectangles—exists only in textbooks and minimalist X11 setups from 1998. Part IV: The Input Gap Let us perform a small experiment in your mind. actual window manager

| System | What You Call It | What It Actually Is | |--------|------------------|----------------------| | Windows 11 | Desktop Window Manager (DWM) | A compositor + policy engine + input router, tightly coupled to the graphics kernel | | macOS | Quartz Compositor (part of WindowServer) | A userspace compositor + event manager + window database | | Linux (GNOME) | Mutter | A Wayland compositor + window manager + input manager | | Linux (KDE) | KWin | The same, but with pluggable window decoration and tiling scripts | | Linux (i3/sway) | i3 or Sway | A tiling window manager that is also a compositor (Sway) or relies on X11 (i3) | But have you ever stopped to ask: what

Who made that cursor appear? Not the terminal emulator—it has no idea your mouse has entered. The window manager did. It noticed the mouse crossing a boundary, sent a WM_MOUSEENTER event (or the Wayland/X11 equivalent), and the terminal responded by changing its cursor. The pure, Platonic "window manager"—a module that only

Thus, the "actual window manager" is not a neutral piece of infrastructure. It is an opinionated choreographer of human attention. If we dig deeper than the compositor, past the input router, beyond the policy engine, we find the kernel and the display server .