Bug introduced in 10.1.0 and fixed in 10.2.0

I am observing a potential bug not present in MMA on Win 7 Ultimate, but observable on MMA 10.1 on Win 7 Enterprise. It seems to work with every Manipulate construct. A very simple example is presented below:

Manipulate[Plot[Sin[a x], {x, 0, 2 \[Pi]}], {a, 1, 10}]

After evaluating this expression, move the slider somewhere towards the right, then click on the little + sign to expand the controls. The slider instantly jumps to the leftmost limit, resetting the setting.

Can anybody confirm such behavior and, maybe, confirm this as a bug?

PS In the case that the problem is not observed by other users, I will be back at work tomorrow European afternoon (where I have 10.1/Enterprise) to give more details.

As correctly observed in the answer to the linked duplicate question, this is a bug of Manipulator, the default control in Manipulate, however it does not seem to be related to PlotTheme or plotting functions. In any case, other users report the bug to be fixed in 10.2, however the problem in 10.1 is more general than just when using DialogInput as in the linked question: it can be reproduced when starting with any manipulator with initially collapsed controls and then expanding them.

  • $\begingroup$ Confirmed. It's fixed in 10.2.0. $\endgroup$
    – ilian
    Jul 20, 2015 at 21:22
  • $\begingroup$ It wasn't like that on v9 :) $\endgroup$ Jul 20, 2015 at 21:23
  • $\begingroup$ @ilian Do you also have Win7 enterprise? To everyone else: can anyone confirm this as 10.1-specific or system specific or whatever? As soon as this is localized, the best possible answer would be to post where and under which OS this happens. Also I'm suprprised, that this question didn't come up before :-) $\endgroup$
    – LLlAMnYP
    Jul 20, 2015 at 21:27
  • $\begingroup$ @LLIAMnYP Not OS specific. $\endgroup$
    – ilian
    Jul 20, 2015 at 21:34
  • $\begingroup$ It was noticed by @halirutan in chat and i also confirmed that $\endgroup$
    – SquareOne
    Jul 20, 2015 at 22:35


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