This test script is to confirm a bug in GIMP or to determine why this is occurring.

When I run the attached test-zero script and set the menu option to zero with the spinner, I get a value like this:
Value: 1.387778781e-15

When I set the menu option to zero using the slider, I actually get zero:
Value: 0

Menu Location: Script-Fu/Test Zero
The Value will be displayed on the Error Console.

1) Start GIMP clean.
2) Create a new image
3) Run: Script-Fu/Test Zero
4) Use spinner to set the value t zero and click OK.

I would appreciate if others would give this a try and post back their results using both the spinner and the slider. Thanks!

[Deleted]

This is what I got, but I'm not sure if I did it correctly.

by Wallace. Here are my results.

@jt - Thanks!

@Molly - Thanks for testing! I see the same issue on your system.


You're the first one who has tested this in Windows. Did you try it with both the spinner and the slider? From my testing, it occasionally gives the correct value with the spinner.

The slider is the bar across the middle, where you slide to change values. The spinner is the box at the end, where you use arrows to spin the values up and down. The slider seems to work correctly and consistently. The spinner appears very inconsistent on my system and only occasionally returns zero.

I thought it might be a GTK problem, but that doesn't appear to be the case now - I've just tried getting double float values from a GTK spinbutton in another C plugin and that doesn't show any anomalies.

What I did find with your test script is that this funny is not confined to value zero - the miniscule residual is present with other values but is comparatively too small to be displayed by (number->string).
For example, if you amend the script to subtract 2.7 from the value passed to the script before displaying the test message and then set the spinbutton to 2.7, the error message again shows some ridiculously small non-zero number (e-15 or smaller). So the residual value is there, just not shown with values other than zero.

Also, it happens even without a slider (ie. if you use SF_ADJUSTMENT with option SF_SPINNER).

I get the same results either way.

@jt - Thanks for your testing. Yes. it seems to only be related to the spinner.

@Wallace - I can't view that video. Asked me to sign in.

I got it to work when I clicked the utube link. Tux

Wallace.I can see the video now. Can you start GIMP from scratch, create a new image, then start test-zero, go right to the spinner and move it to zero, then click OK. Those steps almost always produce the incorrect result on my system. Try it several times.

Perhaps it's a Linux issue and as jontait2 suggested, it's GTK related.

Try the video now. You should be able to see it.

Okay I'll try that.

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I opened Gimp, created an image, ran Test Zero Warning using spinner.
Closed Gimp, reopened Gimp, ran Test Zero Warning using slider.
I get the same results for both tests each time.

Thanks, Wallace.

Maybe a few other Windows users can run the test to confirm your findings.

So far, the problem has been seen on 3 different versions of Linux.

I also ran the test several times. Closing Gimp then reopening Gimp with each test and got the same results each time.

I will boot up in Winsoze and try it.

This is my test run using Windows 7 (64bit)

Tux, I will stay here in Windows until 11:00 in case you want it run again.

Thanks, Molly. You've confirmed the problem exists in Windows, as well.

Most every time I think a problem might be only Linux or only Windows related, it usually turns out not to be the case.

Linux doesn't have issues...