MLVWM is a Macintosh-like virtual window manager for X11 created by
Takashi Hasegawa. It supports monochrome and color modes, including
System 6, MacOS 7, and Mac OS 8-like themes. It provides a customizable,
application-specific menu bar, plus applications & windows menus,
multiple desktops, collapsible windows, and supports "swallowing" other
small X11 applications into the menu bar as widgets.