Random jump to top of topic while pan (middle mouse) scrolling

(Luke S) #1

Something that I have been running into for a while. At random, while scrolling, discourse will dump me at the top of a topic with no warning. This can be from deep in the topic, sometimes dozens of posts down. Has happened on Meta (signed in) and www.what.thedailywtf.com. (Not signed in.) Happens scrolling up or down. To be more precise:


  • When scrolling, sometimes my position in topic is reset to post 1.
  • There is sometimes a small lag, just enough to load the post if it is not in memory.
  • Only happens when scrolling, ie vertical position has to be changing. Never happens when I am sitting still.

Win 7 pro.
Chrome stable (has been happening for some time, multiple Chrome releases)
Not tested in IE - I don’t spend enough time with it to know.

How I Scroll:
I use a lenovo trackpoint, in scroll mode. (Tap center button, get scroll icon. Push trackpoint to scroll)
I have not tried this with a normal mouse, (don’t have one) but the browser should be getting the same signals as if you hold down the center button and move your mouse

EDIT: Some quick googling suggests that this might be called pan scroll mode. I’m in the mode where:

  • If I move the mouse down a little, I scroll down slowly until I get to the bottom of the page.
  • Moving the mouse down a little further increases speed.
  • Moving back up brings be to a stop.
  • Further up, and I scroll up… etc.

(Jeff Atwood) #2

Need more descriptive repro. Retagging as support.

(Luke S) #3

made a couple of edits to hopefully make this more clear. If there is a specific point that you would like clarified, let me know.

(Luke S) #4

Just had this happen to me again. I was in this topic, and got re-directed part of the way up the page. Got a closer look at the process, I noticed what appeared to be a browser page refresh. The time was between 7:53 and 7:58 PM, CST (UTC-6:00) November 13, 2014. Did something change/get updated in that topic that could have triggered a reload?

(Jeff Atwood) #5

Meta redeploys with every checkin so it is possible; see GitHub to identify the times. (Builds and deploys take up to 10 mins after checkin)

(Luke S) #6

Okay, Just took a look at GitHub commit history. Most recent commit before this happened was three and a half hours before my “incident,” so, unless the deploy took a lot longer than normal, probably not it.

I was wondering about events in that particular topic. I note that there are a couple of animations that were added to that thread about two hours beforehand. I note in the .json feed that they are currently hosted locally, but I don’t know how they were originally added.

Slightly hypothetical question: If an image or animation were linked from someplace like imagur and the automated local cache mechanism downloaded the images while someone was viewing the topic, would data be updated for that person’s view?

Not saying that’s what happened. I’m just spitballing here.

(Luke S) #7

Any thoughts on what, if anything I can do to help track why this happens? I still find this disorienting. i know that its hard to troubleshoot when you can’t repo, so is there any way I could automatically collect data as I use the site that might help narrow things down?

Also: Update

  • Today I dropped into an older topic that I had not visited in a while. (Started at my last read point) After a little reading and scrolling, I got bumped to a post just a few up from where I had entered the topic. Upshot: not always taken all the way to the top of the topic.

(Jeff Atwood) #8

I just think very few people use this strange middle mouse button scroll method, which is highly specific to Windows.

(and IMO should not even exist in the first place, I believe it is a concession for mice that have a middle button but no wheel, and is that even possible on any remotely modern mouse hardware?)