541675 - scrolling with mouse wheel scrolls too many lines

Status: UNCONFIRMED

(Core :: DOM: UI Events & Focus Handling, defect)

Description

[Dekel Tal]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 GTB6
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 GTB6

Scrolling some pages using the mouse wheel, scrolls too many lines (I think it scrolls 6 lines instead of 3). This is a regression from version 3.5.

Reproducible: Always

Steps to Reproduce:
1. Navigate to http://www.ynet.co.il/articles/0,7340,L-3837738,00.html
2. Use the mouse wheel to scroll
Actual Results:  
Every mouse wheel step scrolls ~6 lines

Expected Results:  
It should scroll 3 lines by default

This only reproduces on certain URLs (not on every URL, but quite common), but on those specific ones it reproduces consistently. This is seemingly a small problem, but it is however a regression in a feature that is VERY commonly used (mouse wheel scrolling) and makes the user experience on those sites very poor.

Comment 1

[Tyler Downer [He/Him]]

Go to about config, and check these settings:
    *  mousewheel.withnokey.action should be 0
    * mousewheel.withnokey.numlines should be some number greater than 0
Also, before changing, post the value in mousewheel.withnokey.numlines. Then, if that doesn't help, try safe mode.

Comment 2

[Dekel Tal]

I verified that:
* mousewheel.withnokey.action is indeed 0
* mousewheel.withnokey.numlines is 6. Tried changing to 3 - did not solve the problem
* safemode did not solve the problem

Comment 3

[Dekel Tal]

An update - setting:
* mousewheel.withnokey.sysnumlines = false
* mousewheel.withnokey.numlines = 3

causes the mouse wheel to scroll 3 lines consistently. This is, then, a problem with the sysnumlines behavior - the set to true, doesn't scroll consistently.

Comment 4

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

This behavior is designed so, if you didn't customize system scrolling speed settings.

I looked same post in Japanese community. So, the override system confuses some users. They really know the way to control the scrolling speed in system settings, but they cannot control the scrolling settings.

We imitated WebKit's behavior (i.e., ignores the system settings) which is bad manner. Maybe, this was our fault...

I think that we should limit the behavior more if there are better ideas that we can know whether the user know the settings in system wide.

Comment 5

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

I have an idea. If users change the system settings, we can disable the override system in pref level.
* Merit: If the user tries to control the speed when Fx is running, we can honor the user's will.
* Demerit: If Fx isn't running at that time, we cannot detect it. And we cannot set the information between two or more profiles.

Comment 6

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Dekel:

You can turn of the override system by mousewheel.system_scroll_override_on_root_content.enabled in about:config.

Comment 7

[Wayne Mery (:wsmwk)]

IS this still an issue?

(In reply to Tyler Downer [:Tyler] from comment #1)
> Go to about config, and check these settings:
>     *  mousewheel.withnokey.action should be 0
>     * mousewheel.withnokey.numlines should be some number greater than 0
> Also, before changing, post the value in mousewheel.withnokey.numlines.
> Then, if that doesn't help, try safe mode.

I cannot find these prefs using a current nightly?

Comment 8

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

They are now "mousewheel.default.delta_multiplier_[xyz]" since native wheel events on macOS doesn't represent amount of scroll with "lines".
https://wiki.mozilla.org/Gecko:Mouse_Wheel_Scrolling#Preferences_for_customizing_delta_values_and_default_action

Additionally, we have "Override system of system scroll speed" pref (used only on Windows, but available on any platforms):
https://wiki.mozilla.org/Gecko:Mouse_Wheel_Scrolling#Override_system_of_system_scroll_speed