FrontEndDynamicExpression
is a global front end option that specifies an expression to be dynamically updated whenever the front end is running.
Details

- FrontEndDynamicExpression->Dynamic[expr] causes the expression to be tracked and updated in the usual way, except that expr is not displayed anywhere.
- FrontEndDynamicExpression can be set on any valid front end object such as $FrontEnd or $FrontEndSession.
Examples
open allclose allBasic Examples (1)Summary of the most common use cases
Run a dynamic expression that prints the number of open notebooks:

https://wolfram.com/xid/0bh04e12vggr5u-1h0ix6
Restore the default value of FrontEndDynamicExpression:

https://wolfram.com/xid/0bh04e12vggr5u-bcrw4q
Properties & Relations (2)Properties of the function, and connections to other functions
Dynamic can be omitted from the right-hand side if :> is used in SetOptions:

https://wolfram.com/xid/0bh04e12vggr5u-m6ytc
Similarly, Dynamic can be omitted from the right-hand side if := is used in CurrentValue:

https://wolfram.com/xid/0bh04e12vggr5u-hgvkzn
As with any other Dynamic expression, Refresh may be used to control reevaluation:

https://wolfram.com/xid/0bh04e12vggr5u-ca3f5k
Wolfram Research (2010), FrontEndDynamicExpression, Wolfram Language function, https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html.
Text
Wolfram Research (2010), FrontEndDynamicExpression, Wolfram Language function, https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html.
Wolfram Research (2010), FrontEndDynamicExpression, Wolfram Language function, https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html.
CMS
Wolfram Language. 2010. "FrontEndDynamicExpression." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html.
Wolfram Language. 2010. "FrontEndDynamicExpression." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html.
APA
Wolfram Language. (2010). FrontEndDynamicExpression. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html
Wolfram Language. (2010). FrontEndDynamicExpression. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html
BibTeX
@misc{reference.wolfram_2025_frontenddynamicexpression, author="Wolfram Research", title="{FrontEndDynamicExpression}", year="2010", howpublished="\url{https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html}", note=[Accessed: 07-July-2025
]}
BibLaTeX
@online{reference.wolfram_2025_frontenddynamicexpression, organization={Wolfram Research}, title={FrontEndDynamicExpression}, year={2010}, url={https://reference.wolfram.com/language/ref/FrontEndDynamicExpression.html}, note=[Accessed: 07-July-2025
]}