Actual Window Manager _top_ May 2026

You move your mouse over a terminal window. You click. A cursor appears.

On Linux (Wayland), the kernel's DRM (Direct Rendering Manager) and KMS (Kernel Mode Setting) control the actual display hardware. The compositor talks to DRM via libdrm to flip buffers. On Windows, the DWM talks to the DXGI kernel driver. On macOS, WindowServer talks to the IOKit framebuffer. actual window manager

At this level, there are no windows. There are buffer objects, page flips, and scanout engines. The window manager is a ghost in this machine—a high-level construct that the kernel does not recognize. You move your mouse over a terminal window

| 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) | On Linux (Wayland), the kernel's DRM (Direct Rendering