Manipulate slider unresponsive after suspend in Linux

Question

Bug fixed in Mathematica 11

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I've tested Linux Mathematica versions 7-9 on various Linux distributions, with identical problem: after suspend/resume cycle my Manipulate controls (i.e. sliders&buttons) appear unresponsive, though I can enter the values manually. This looks much like this question, but before suspend I can use the controls normally, and if they stop working, restarting Mathematica also helps (killing and restarting math kernel doesn't help). Easy way to test this would be using this code:

Manipulate[Plot[a x, {x, -3, 3}, PlotRange -> {-1, 1}], {a, -1, 1}]

Then making the machine suspend to RAM, waiting 5 seconds and resuming it. If the controls still work (I rarely encounter such situation), second suspend does kill them.

Does anyone reproduce this problem? Are there any better workarounds than restarting Mathematica UI?

Answer 1

I've also noticed this bug, although buttons/drop down menus do continue to work, for me only sliders become unresponsive after suspend (Ubuntu 12.10/Mathematica 9.0.0.0 x86 64 bits).

A possible workaround is thus to change all parameter controls to buttons/dropdown menus by providing a finite list of values the parameter is allowed to take:

Manipulate[Plot[a x, {x, -3, 3}, PlotRange -> {-1, 1}], {a, Range[-2,2,.5]}

Let's hope someone at Wolfram notices this thread! Have you already filed a bug report?

Answer 2

Another workaround, which allows to still have slider-like input, but is currently a bit inconvenient (ideas (with code) to improve are welcome!), is making a custom control. I've taken this answer as a starting example and reworked it to make it function when LocatorPane and the like don't work.

It appears that MousePosition and EventHandler still appear to work even when this bug is active. So, here's the code for the custom control:

customSlider[Dynamic[i_], str_, b_, e_] :=
 Dynamic[
  With[{diskSize = Abs[e - b]/60},
   EventHandler[
      Graphics[{Red, Disk[{i, 0}, diskSize]}, 
       PlotRange -> {{b, e}, {-diskSize, diskSize}}, 
       Axes -> {True, False}, ImageSize -> 300, Background -> None, 
       ImagePadding -> 10, PlotLabel -> Row[{str, i}]],
    {"MouseMoved" :> (If[Abs[Last@#] < diskSize, i = First@#]&@MousePosition["Graphics"])}
    ]
   ]
  ]

And here's how to use it with the example in the OP:

Manipulate[Plot[a x, {x, -3, 3}, PlotRange -> {-1, 1}],
    {{a, 0}, (customSlider[#1, "a=", -1, 1] &)}]

It looks like this:

To use it, just move the cursor in the scale, and the red disk will follow it. I tried using "MouseDragged" as the event, but it works strangely and isn't really usable. Another possible alternative is to use "MouseClicked". Even better might be to somehow make a local active variable and set it to True on MouseDown, False on MouseRelease and work according to this, but I failed to make Dynamic work with Block/Module...

EDIT

It appears that "MouseDragged" doesn't work as expected because while the mouse button is pressed, no events are generated at all. Thus the only way I see to have some sort of "click to start drag" process is using keyboard keys instead of mouse buttons, i.e. checking state of keyboard keys such as Ctrl via CurrentValue["ControlKey"] and only setting i if it returns True.

Answer 3

This problem appears to have been fixed in Mathematica 11.0.