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Unexpected undo behavior

PostPosted: November 14th, 2017, 3:00 pm
by lifeisawesome
Say you have this pattern: Image.
Afterwards, step a generation and this happens: Image.
Finally, press Ctrl-Z.
This is the expected result: Image
This is the actual result: Image

Re: Unexpected undo behavior

PostPosted: November 14th, 2017, 3:39 pm
by Cclee
just for reference what rule is this

Re: Unexpected undo behavior

PostPosted: November 14th, 2017, 4:15 pm
by BlinkerSpawn
Cclee wrote:just for reference what rule is this

This is in Life, and I can't replicate this bug.

Re: Unexpected undo behavior

PostPosted: November 14th, 2017, 4:37 pm
by dvgrn
Could someone post the images locally by attaching them to a message? All I can see from my current location is the following -- this is a direct copy and paste:

Say you have this pattern: Image.
Afterwards, step a generation and this happens: Image.
Finally, press Ctrl-Z.
This is the expected result: Image
This is the actual result: Image

By editing the message I can see that these are i.cubeupload.com links. I don't _think_ there's really any need to do this kind of external image hosting, at least for most cases. If you attach image files directly to the message and then click the "Place inline" link, you can get pretty much the same effect as an [img] tag. (?)

I'm very interested in Undo bug reports. There's a rare problem with the Undo system that I haven't been able to come up with steps to reproduce, for half a dozen Golly versions now. So don't just give up if it can't be reproduced immediately, please!

There was some hope for a while that the Undo problem was found and fixed, but I'm pretty sure I've seen it happen in Golly 3.0 and 3.1 now -- along with the other problem where clicks on menu and toolbars are interpreted as clicks in the universe grid under that control.

(That second bug goes away when you minimize and re-display the Golly window, so it's a cosmetic issue, relatively speaking. But the Undo problem can really make you lose work sometimes.)

Re: Unexpected undo behavior

PostPosted: November 14th, 2017, 4:59 pm
by danny
dvgrn wrote:Could someone post the images locally by attaching them to a message?

Here's the whole post:
post.png
post.png (6.17 KiB) Viewed 3535 times

Re: Unexpected undo behavior

PostPosted: November 14th, 2017, 6:15 pm
by dvgrn
danny wrote:
dvgrn wrote:Could someone post the images locally by attaching them to a message?

Here's the whole post...

Thanks! Yeah, I've certainly never seen a set of steps as simple as that produce any bad Undo behavior, and I am unable to reproduce the problem on Golly 3.1/ Windows 7.

The Undo difficulties I've seen have to do with rolled-back changes getting offset by a few cells from their correct location. Usually the offset seems to be a standard scroll-bar step distance, for the current zoom level. And it usually happens only after a fairly complex set of editing steps, and often also a rule change (Life to LifeHistory or vice versa).

Once the bad offset gets into the Undo/Redo system, however that happens, it's possible to run backward with Ctrl+Z and forward with Ctrl+Shift+Z and see the incorrect series of changes happen over and over again.

It seems barely possible for lifeisawesome's reported bug to have been caused by this Undo offset problem. But it would probably be repeatable only until the next File > New or closing and re-opening Golly, not after that.

@lifeisawesome, what operating system and Golly version are you seeing this on? If the problem happens consistently, can you copy and post your starting pattern out of Golly, if it's something different from

x = 3, y = 3, rule = B3/S23
2o$b2o$bo!

?

Re: Unexpected undo behavior

PostPosted: November 15th, 2017, 4:15 pm
by lifeisawesome
Nevermind, it randomly fixed itself.