Bug introduced in 10.3 or earlier, fixed in 10.4.

When the + opener is opened, two things happen:

x = 0;
Manipulator[Dynamic[x, (Print[#]; x = #) &], {-10, 0}]

enter image description here

  1. the actual manipulator value # is set to be the minimum of the range;
  2. the second argument of Dynamic gets evaluated.

However, when the range is set to e.g. {-10, 10}, the behavior is correct. Manipulator had a ragged history recently, check these related threads out:

While somwe were ironed out, something more basic still lurks in Manipulator.

(Mathematica 10.3, Win 7 64)

  • 2
    $\begingroup$ Comments in one of linked topics are quite on point. I really like: Manipulator[1] $\endgroup$
    – Kuba
    Dec 2, 2015 at 15:27
  • 1
    $\begingroup$ Thanks @Kuba, I'm aware of that, but I wanted to show that Manipulator not just resets the value but also evaluates anything else - which is scary, as always. $\endgroup$ Dec 2, 2015 at 15:29
  • 1
    $\begingroup$ Using a range of {-10, 0.01} is interesting, too. $\endgroup$
    – Karsten7
    Dec 2, 2015 at 15:33
  • 1
    $\begingroup$ Submitted for TechSupport. $\endgroup$ Dec 2, 2015 at 15:38
  • 1
    $\begingroup$ A gif that demonstrates the new issue for this input. $\endgroup$
    – Karsten7
    May 7, 2016 at 14:29

1 Answer 1


Bug was fixed in version


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