This is partly historical. When MultiFinder was introduced to System 6, the Mac's primary difference from the PCs of the era was an emphasis on mouse manipulat

This is partly historical. When MultiFinder was introduced to System 6, the Mac's primary difference from the PCs of the era was an emphasis on mouse manipulation, instead of keyboard manipuation (via DOS's command line, mostly). It was expected for end users to use drag-and-drop to move information between applications, instead of using the clipboard. (Something that Apple themselves didn't fully come through with regarding APIs until System 7.) Since drag-and-drop requires visible targets to work, and users were expected to have to see data from two or more apps at the same time, it was considered "rude" to take up the entire screen. (Even apps that tried to do so were constrained by the OS to provide a 4-pixel gutter around the edges of the screen so the user could always option-click the Finder to the foreground.) The notion that you only do work in just one app was considered "missing the point" for multitasking, which is part of the reason the original "Switcher" metaphor for multitasking in the classic Mac OS was abandoned. http://folklore.org/StoryView.py?story=Switcher.txt http://folklore.org/StoryView.py?story=Switcher.txt Upshot: Apple's UI designers seem to regret adapting the newspaper publisher's concept of the clipboard, and have been trying to invent workarounds ever since, probably because it's a form of "hidden state." (See iPhone 1.x and 2.x for a more recent example.) The only time in recent memory Apple acknowledged the validity of a clipboard model was when they tried to adapt it to a "publish and subscribe" dynamic system in System 7, only to give up when implementation and UI complexities with the concept rendered that unpopular.