1272991 - Arrowscrollbox processes PageUp/PageDown mouse wheel events incorrectly.

Status: VERIFIED DUPLICATE of bug 1251980

(Firefox :: General, defect)

Description

[Dook]

User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0
Build ID: 20160502172042

Steps to reproduce:

1) Set mouse scroll in windows control panel to "one screen at a time".
2) Open the bookmarks popup menu (or any other arrowscrollbox list) in the main menu. Bookmarks must be a sufficient number (e.g. 100).
3) Make one scroll the mouse wheel down or up.



Actual results:

It will scroll to the beginning(top) or end(bottom) of the list.


Expected results:

Scroll one page up or down.

Comment 1

[大沼 良優]

I confirmed this bug.

environment 

windows10,firefox 46.0.1

Comment 2

[Andrew Overholt [:overholt]]

I think this is a frontend bug. See bug 1257815 for more information.

Comment 3

[Dook]

Maybe, becаuse: 
"I've tested again, and I realize that the element type <arrowscrollbox> is the criminal who don't respect "one page scroll" feature.

    http://mxr.mozilla.org/mozilla-central/source/toolkit/content/widgets/scrollbox.xml#469
    http://mxr.mozilla.org/mozilla-central/source/toolkit/content/widgets/scrollbox.xml#303

When you move the wheel, DOMMouseScroll event is fired. The event has a property named "detail", and the value indicates how many lines we should scroll in the box. On <tree> or <listbox>, "event.detail" says correct value. However, on an <arrowscrollbox> element, when I set "mousewheel.withnokey.action" to "1", then "event.datail" is "2" on my environment. After I set "mousewheel.enable_pixel_scrolling" to "false", then "event.datail" is "32768" (equals to 215 - this is quite odd!) Both values are wrongly generated by Firefox itself.

Similar issues:
    https://bugzilla.mozilla.org/show_bug.cgi?id=543338
    https://bugzilla.mozilla.org/show_bug.cgi?id=723132

Now I'm reserching why the "event.detail" became an invalid value "32768"".

- quote from here:  https://github.com/piroor/treestyletab/issues/262#issuecomment-5505560

Comment 4

[arni2033]

(In reply to Andrew Overholt [:overholt] from comment #2)
> I think this is a frontend bug. See bug 1257815 for more information.
This isn't frontend bug. Given that nobody in frontend ever knew about Masayuki Nakano's ingenious invention, all sites and even Firefox itself were broken for years.
It is a backend bug, even though for 5+ years Masayuki Nakano wanted me to encounter that bug (he carefully implemented for me) everywhere without even a workaround in about:config. Again, it's bug in
API, because Webkit/Blink uses API that proved to be good, and Firefox uses API that proved to be bad.


@ Dook (reporter):
This bug was there all along, because Firefox developers didn't know their browser good enough.
They used DOMMouseScroll event (backend stuff) in frontend: <arrowscrollbox> and more!, but not in <tree> and <listbox> UI elements. The creator of DOMMouseScroll event (Masayuki Nakano) has intentionally built a trap to break our (your and mine) UX, and frontend devs were unaware of it.

Currently (Firefox Nightly 49), <arrowscrollbox> including bookmark 'panel' don't use DOMMouseScroll, but there's still bug. Please reopen this bug if it's different from issues mentioned in bug 1251980.