:   '''[after] idle''' ''script'' ?''script script ...''?

Concatenates the ''script'' arguments together with space separators (just as in the '''[concat]''' command), and arranges for the resulting script to be evaluated later as an idle callback. The script will be run exactly once, the next time the event loop is entered and there are no events to process. The command returns an identifier that can be used to cancel the delayed command using '''[after cancel]'''. If an error occurs while executing the script then the '''[bgerror]''' mechanism is used to report the error.
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A typical use of this command (and perhaps the most important one) is when you need to [keep a GUI alive during a long calculation]. This is often done with the [update] command, but this slows down your computation and update is no good choice because: [Update considered harmful]. Instead use something like
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after idle [list after 0 $myCommand]
======
where `$myCommand` does one step of a multi-step calculation and calls the above line after having done the single step until all steps are finished. This will smoothly keep your GUI alive and is no performance hit like [update] or [update idletasks].
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**See also**
   * [after]
   * [after cancel]
   * [after info]
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