Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

FF17 Mouse wheel line scrolling too fast, alt+scroll missing

  • 8 replies
  • 24 have this problem
  • Last reply by drabun

more options

Upgraded to FF17 from FF16. Noticed that when I scroll w/ my mouse it jumps about 5 or 6 lines, versus 16's 3 or so. Also, the old mouse shortcut of alt+mousescroll to scroll line by line is gone. A google search netted me the Gecko wiki explaining all the new mouse scrolling options under about:config, but it was mostly over my head. One part I did understand is the loss of the old "mousewheel.withnokey.numlines" and "mousewheel.withnokey.sysnumlines" strings.

I figured it out by changing mousewheel.system_scroll_override_on_root_content.enabled to "false", and it is working at the same speed as it did under FF16, but the ability that alt+mousescroll provided is still missing. Having the ability to customize the mouse scroll speed (instead of turning off the system scroll override) is still outside of my grasp as well.

All Replies (8)

more options

You can set the scroll amount for the mouse wheel via mousewheel prefs on the about:config page

mousewheel.withnokey.numlines = 2
mousewheel.withnokey.sysnumlines = false

Look at this pref to set the scrolling behavior with the keyboard.

toolkit.scrollbox.verticalScrollDistance (3)

There are extensions that work both for the mouse and the keyboard to set the scroll amount, but they can only be set to scroll an amount of pixels and not to scroll one line regardless of font-size (height) of the text.

more options

Thank you for your reply. I apologize for my miscommunication on my original post, but I meant to say that that the "mousewheel.withnokey.numlines" & "mousewheel.withnokey.sysnumlines" no longer work for me under FF 17. If I r-click and choose "Reset", the lines completely disappear from about:config & the mouse wheel scrolling continues to jump too far, until I changed this line


It changes back to the slower FF 16 mouse scroll speed. The problem now is, if I want to change the scroll speed to something else, the Mozillazine instructions no longer work.

Scrolling behavior w/ the keyboard is fine. I am unable to use any type of smooth scrolling, as it makes me motion sick.

more options

There seem to be different prefs, one for the scroll amount and other for the various axes (x, y, z)


So you can modify the mousewheel.min_line_scroll_amount pref to specify how many lines to scroll.

more options

I thought the same thing when I saw that min_line_scroll setting, and I changed the numbers around, but no such luck.

Playing around w/ the delta modifiers DOES change the mouse scroll speed, though it would be nice for a more user-friendly explanation. Changing the "y" value to something lower than 100 changes the scroll speed to 1 line, no matter what. Changing any values on "x" to anything other than 100 while "y" is not set at 100 still creates the 1 line scroll speed. Putting the "y" value back to 100 & playing around w/ the "x" value DOES change the scroll speed beyond 1 line scrolling, though guessing how many lines it scrolls is not readily apparent. However, thank you for the idea of playing w/ the delta settings.

Anything else would be the alt+scrolling feature that seems to be gone. The Gecko wiki on mouse scrolling no longer has the option to scroll line per line, as it did w/ previous FF versions.

more options

Modified by cor-el

more options

Yes, I was reading that before posting and had some difficulty making sense of it. Now, after our conversation here & playing w/ the default delta multipliers earlier, I played w/ the "y" alt.delta_multiplier & *think* that I'm back at scrolling one line at a time w/ alt held down (36). I'm still not sure though, since I do not understand how the values work.

But, thank you for all the help! I take it I'll need to go another route for suggestions on future FF releases? Having a more user friendly way on changing mouse scroll speed would be helpful.

more options

There are some test cases that Mozilla uses to make sure that Firefox is working properly.

Note that you normally want to modify the vertical (y) axis and not the horizontal (x) axis delta_multiplier values.
The delta_multiplier are internally floats of type double and are converted to an integer for the prefs by multiplying them with 100.

Modified by cor-el

more options

~ = mousewheel.system_scroll_override_on_root_content

` = mousewheel

basically, the num of lines to scroll becomes relative to OS wheel setting. we used to be able to specify it explicitly through `.<modifier-key>.numlines, when `.<modifier-key>.sysnumlines = false

now, we always specify percentage of the OS wheel-line through the new `.<modifier-key>.delta_multiplier_<direction>. eg. if your OS wheel-line is 4, then to vertically scroll 2 lines per wheel event, set `.<modifier-key>.delta_multiplier_y to 50

while the above is per modifier key, ~.* apply a percentage of the OS wheel-line for no/any modifier key

  • if ~.enabled = false, then `.<modifier-key>.delta_multiplier_<direction> is used
  • if ~.enabled = true: if ~.vertical.factor >= `.<modifier-key>.delta_multiplier_y, then use ~.vertical.factor, otherwise use `.<modifier-key>.delta_multiplier_y (same goes for horizontal scroll)

in essence, if ~.enabled = true, choose the bigger percentage to apply, not both, for each direction, for each modifier key

btw, don't take my words for those behaviors, i got that accidentally while i was trying to figure out how to mouse-scroll by pages/by pixels (which i failed, any idea?)

i quote this from source: pref("mousewheel.min_line_scroll_amount", 5) // If line-height is lower than this value (in device pixels), 1 line-scroll scrolls this height.