Older versions of Mac OS X created separate window objects in memory (just like for app windows) for every file icon on the Desktop. If you had many files showi

Older versions of Mac OS X created separate window objects in memory (just like for app windows) for every file icon on the Desktop. If you had many files showing on the Desktop, it could slow the computer down significantly. You could verify that the icons were separate windows by hitting Shift-Command-4 and then pressing Space to prepare to take a screenshot of the window under the mouse – each icon lit up in blue individually when you moved the mouse over them. If you try it in a modern version of Mac OS X, you’ll see that the Desktop is all one window now – the problem is fixed.