I frequently use SynchronousInitialization -> False when I have time consuming initialization in a Manipulate expression. I was wondering how I could change the label "Evaluating Initialization..." to, say, "Wait please..."?

 {x, 0, 1}, 
 SynchronousInitialization -> False, 
 Initialization :> (Pause[1])]

enter image description here

  • $\begingroup$ I do not see an option in SynchronousInitialization to change this. may be you could send WRI a feature request to add such option to change the message. $\endgroup$
    – Nasser
    Nov 9, 2017 at 1:58

1 Answer 1


not recommended approach

With Method -> {"TemplateExpand" -> True} you can inspect whole structure of created boxes.

, SynchronousInitialization -> False
, Initialization :> (Pause[1])
, Method -> {"TemplateExpand" -> True}

and find out that this preview is defined in Manipulate`Dump`initDisplay. So here's a quick helper function to replace it:

] := RawBoxes[
  ToBoxes[manipulate] /. 
   HoldPattern[Manipulate`Dump`initDisplay[False]] -> newInit

 Manipulate[body, SynchronousInitialization -> False, 
  Initialization :> (Pause[1]), Method -> {"TemplateExpand" -> True}],
 Row[{ProgressIndicator[Appearance -> "Percolate"], "Please wait..."}]

enter image description here

It works but it is not a recommended way, consider it an exercise.

recommended approach

What you should do it to take it in your hands and do something like:

DynamicModule[{initDone = False}
, Panel @ Dynamic[
    If[ Not @ TrueQ @ initDone
    , Row[{ProgressIndicator[Appearance -> "Percolate"], "Please wait..."}]
    , body
  , TrackedSymbols :> {initDone}
, UnsavedVariables :> {initDone}
, SynchronousInitialization -> False
, Initialization :> (Pause[1]; body = "whatever"; initDone = True)

Read more in closely related:

Working with DynamicModule: Tracking the progress of Initialization

  • $\begingroup$ I used your code in a simple way, as a "wrapper" with body = Manipulate[...] and work well as I wanted. Thanks. $\endgroup$
    – wmora2
    Nov 9, 2017 at 15:27

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