It debuted in System 7.5,1 but disappeared in Mac OS 8, when the feature was implemented as a part of the Appearance Manager. A widget was added to the title bar in addition to the double-click method of collapsing a window. The entire feature disappeared with the release of Mac OS X; windows could be minimized to the Dock on the new system or, starting with Mac OS X 10.3, moved aside with Exposé. However, several third-party utilities, such as WindowShade X for Unsanity's Application Enhancer software, have brought the ability back to Mac OS. It has since reappeared as a commercial haxie (an unofficial modification to system software) and offers other features, like translucent windows and minimize-in-place. WindowShade X from Unsanity stopped working in Mac OS 10.7, and other third-party developers have since released applications such as WindowMizer from RGB World that keep the WindowShade feature working on Mac OS X 10.6 and greater.
The WindowShade control panel itself stems from a third-party utility originally written for System 6.0.7 by Rob Johnston. Apple purchased the rights to this software from the developer for use in System 7.5.2
Some window managers for Unix-like operating systems have a similar feature allowing windows to be set to "roll up" when the user double-clicks the title bar of a window.3 Some window managers provide a titlebar button to access the functionality. While Microsoft Windows does not expose such a feature by default, in some versions if a window is minimized while no taskbar is available, the said window will become a "shade" at the bottom of the screen. An intentional shading implementation for Windows is provided by third-party software vendors.
"Three things OS X could learn from the Classic Mac OS". http://www.macworld.com/article/1138335/macat25_classicmacos.html ↩
"System 7.5 and Mac OS 7.6: The Beginning and End of an Era". http://www.lowendmac.com/sable/06/0215.html ↩
"What Is the X Window System". http://linuxdevcenter.com/pub/a/linux/2005/08/25/whatisXwindow.html ↩