Resizing or moving Notebook window causes Manipulate to update its argument

Question

Bug introduced in 10.0 and fixed in 10.3.0

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Check this example:

Manipulate[Grid[{{RandomReal[10]}, {Plot[Sin[x], {x, 0, 2 Pi}]}}], {a, 1, 3}]

As you can see, moving or resizing the Notebook window causes Manipulate to update its argument.

Is this normal behavior of MMA?

Thanks

Answer 1

I think I've found the guilty : this is PlotTheme

Since the problem seems to only occur when "plot" functions are involved, for example here :

Manipulate[Grid[{{RandomReal[10]}, {Plot[Sin[x], {x, 0, 2 Pi}]}}], {a, 1, 3}]

Manipulate[Grid[{{RandomReal[10]}, {ListPlot[Range[10]]}}], {a, 1, 3}]

Manipulate[
 Grid[{{RandomReal[10]}, {ParametricPlot[{Cos[t], Sin[t]}, {t, 0, Pi}]}}], {a, 1, 3}]

but not in other cases, in particular when other type of graphics are used, like here :

Manipulate[Grid[{{RandomReal[10]}, {RandomReal[10]}}], {a, 1, 3}]

Manipulate[Grid[{{RandomReal[10]}, {Graphics[Disk[]]}}], {a, 1, 3}]

and as there is no problem with version 9, and since PlotTheme was introduced in version 10, I just tested PlotTheme->None, and the problem disappears.

For example :

Manipulate[
 Grid[{{RandomReal[10]}, {Plot[Sin[x], {x, 0, 2 Pi}, PlotTheme -> None]}}], {a, 1, 3}]

Answer 2

This bug has been fixed in Mathematica v10.3.

Answer 3

I consider this a bug. Although I have no solution, I can provide some further insights. The behavior seems to depend on the usage of any plotting command or commands that display something. The smallest example I could find is

Dynamic[{Plot[Null, {a, 0, 1}], AbsoluteTime[]}]

A simple static Graphics seems not enough, but if you use a Graph instead of the Plot, the behavior appears too. If you look at the cell expression, there seems nothing unusual there

Cell[BoxData[
 DynamicBox[ToBoxes[{
    Plot[Null, {$CellContext`a, 0, 1}], 
    AbsoluteTime[]}, StandardForm],
  ImageSizeCache->{404., {46., 51.}}]], "Output",
 CellChangeTimes->{3.6323472127299213`*^9}]

Therefore, the question is why the front end does trigger a re-evaluation of this DynamicBox.

Answer 4

EDIT: Everyone reading this should be aware that SquareOne's answer contains the real reason and the best way to get rid of these unwanted updates. I'll leave my answer here as I think it shows useful techniques to avoid unwanted updates in similar cases but using PlotTheme->None is certainly the best solution to the OPs problem...

It probably could be argued that the version 10 behavior is OK as the window size might cause changes in any of the manipulates content, e.g. when using something like ImageSize->Full or CurrentValue[EvaluationNotebook[], WindowSize]. The updates when a window moves could then be explained by details of how WindowSizes and WindowMarging are internally handled which would also explain why that seems to be platform dependent. On the other hand it seems to be a confirmed bug and I certainly would consider this an inacceptable misbehavior when using an explicit TrackedSymbols:>{a} to either the Manipulate or an additional Dynamic wrapper for the Plot.

Apart from that I wanted to share a workaround which seems to avoid the problem but is quite some effort to implement in more complicated cases:

DynamicModule[{output, lastValue},
  Manipulate[
    DynamicWrapper[
      output,
      If[lastValue=!= a,
        lastValue = a;
        output = Plot[Sin[x], {x, 0, 2 Pi}, 
           PlotLabel -> {a, RandomReal[]}, 
           ImageSize -> {500, 500./GoldenRatio}
        ]
      ],
      TrackedSymbols :> {a}
    ],
    {a, 1, 3}
  ]
]

the following might make the workaround easier to apply to a larger amount of code:

SetAttributes[saveDynamic,HoldAll];
saveDynamic[expr_,TrackedSymbols:>{symbol_Symbol}]:=DynamicModule[{lastValue,output=""},
    Column[{
    DynamicWrapper[
        Dynamic[output,TrackedSymbols:>{output}],
        If[lastValue=!=symbol,
            lastValue=symbol;
            output=expr
        ],
        TrackedSymbols:>{symbol}
    ]
    }]
];

One could of course adopt this to accept more than one tracked symbol and only use that definition instead of a standard Dynamic for those versions which show the erronous behavior.