This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)


is an option for Dynamic, DynamicModule, Manipulate and related constructs, which specifies an expression to be evaluated when the construct can no longer be displayed or used.
  • The typical usage is Deinitialization:>expr.
  • Deinitialization is typically done when the cell containing a construct is deleted, or when the notebook containing it is closed.
  • Deinitialization will never be performed unless initialization has previously been performed.
  • Deinitialization may be delayed if, for example, a construct appears in an invisible location such as the clipboard.
Choose a color and create the colored disk when the window is closed:
Temporarily change the background of a notebook:
Track and display how long a window was viewed:
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