1769061 - Change system setting of mouse scroll speed does not apply on Firefox

Status: RESOLVED INCOMPLETE

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

Description

[steveguory]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.54 Safari/537.36 Edg/101.0.1210.39

Steps to reproduce:

Just installed Firefox 100, 64bit on Windows 11 21H2. Noticed that the mouse scroll speed in Firefox is wrong in all pages. I changed system setting before because I felt the mouse scroll speed was too slow to me. But Firefox does not seem to apply the changed mouse scroll speed.

Actual results:

I restarted Firefox, but the problem still exist. I checked on Edge, the mouse scroll spend is what it should be, it works fine on Edge.

Expected results:

The mouse scroll speed in Firefox should be as same as the system setting that I have changed. Now in Firefox it seems like the mouse scroll speed is the default setting that has not changed.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::DOM: UI Events & Focus Handling' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

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

Gecko refers system settings of the scroll speed, but the computation is different from the others.

Gecko respects font size of the scrollable element because Windows' scroll speed is defined as how many lines (or pages) should be scrolled when mouse wheel is turned a tick. The default value of Windows is 3 lines, but Gecko users 6 lines for making same (similar) scroll speed as the other browsers (i.e., the other browsers started to ignore the default system scroll speed for making their users use faster web browser). Then, with the dilemma between the other browsers' scroll speed vs. users' settings mainly for heavy users, we considered that using the x2 faster scrolling is only when users (or the mouse drivers) do not customize the scrolling speed (i.e., both vertical/horizontal scroll speed are 3 lines), otherwise, follow the users' settings as-is (i.e., scroll 4 or 5 lines per tick is slower than 3 lines).

So I think that your system settings are not set to 3 lines because you feel only Firefox's scroll speed. Could you check the settings in your environment? You must be able to refer it in your system's scroll setting UI. And also you can refer the raw value in the registory, run regedit.exe, and check WheelScrollChars and WheelScrollLines in HKEY_CURRENT_USER\Control Panel\Desktop. Could you let us know what values are set to them?

Comment 3

[steveguory]

I checked that the WheelScrollChars WheelScrollLines in regedit.exe are both set to 3. The Wheel scroll lines should be 5.

(My system language is not English so the name of settings below might not be translated correctly.)

The way I change my mouse scroll lines is in Windows setting (press Windows key + I) - Bluetooth&other devices - Mouse - Scrolling - Scroll lines(which is set to 5 here).

I don't know if it's normal. 5 (in the setting) is not equal to 3 (in the regedit). Its kinda confusing. I checked again on 'Edge' ver 101.0.1210.47 and 'Chrome' ver 101.0.4951.67, scroll lines for these two browsers are normal. Only Firefox's scroll line is different.

Comment 4

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

(In reply to steveguory from comment #3)

I checked that the WheelScrollChars WheelScrollLines in regedit.exe are both set to 3. The Wheel scroll lines should be 5.

Thanks. As I said, 4 or 5 is slower than the default settings 3. Only the 3 case is "boosted". If you'd like to set the scroll speed 5 lines in the system-wide, but you'd like Firefox to scroll 10 lines, then, you need to change mousewheel.default.delta_multiplier_y (and also _x for horizontal scroll) to 200.

I don't know if it's normal. 5 (in the setting) is not equal to 3 (in the regedit). Its kinda confusing. I checked again on 'Edge' ver 101.0.1210.47 and 'Chrome' ver 101.0.4951.67, scroll lines for these two browsers are normal. Only Firefox's scroll line is different.

Note that if the scrollable element has smaller font size than 16px, the scroll speed is slower than the other browsers. This is by design at least for now.

Could you try to change the above prefs in about:config of Firefox?

Comment 5

[Hsin-Yi Tsai (she/her) [:hsinyi]]

Close as INCOMPLETE because we can't make further action without hearing back from comment 4.