247531 - When smooth scrolling is enabled, synchronized scrolling of 2 divs is jerky

Status: NEW

(Core :: DOM: Core & HTML, defect, P5)

Description

[Pablo]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040616
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040616

I have developed a page with two divs that must be syncronized when a javascript
onscroll event occurs. This works fine in Mozilla for Linux but in the win
version there are a little "unsync" when the user press scrollbars up and down
arrows (this doesn't ocurrs when the users use de scroll bar slider).

Reproducible: Always
Steps to Reproduce:
1. Create a page with two divs (overflow auto)
2. Make the two divs sync when a onscroll events occurs
3. Push down arrow on a div an see how the other is "unsync" scrolling the content.

Actual Results:  
When the user press the scrollbar arrow key of one div the other get unsync at
onscroll event.

Expected Results:  
Make the two divs get sync when the user press up and down arrows in a div with
overflow:auto

Comment 1

[Pablo]

Attachment: A page with two div and a jscript function to sync the onscroll event

Here you can see the actual results (remember to user Mozilla under a Windows
instalation to see the bug in action).

Comment 2

[Brendan Eich [:brendan]]

Please report DOM bugs against the DOM, not the JS engine.

Someone with a Windows box will have to confirm this.

/be

Comment 3

[Gérard Talbot]

The testcase WORKSFORME: I get the expected results. Mozilla 1.7 final release
(build 20040616) under XP Pro SP1a here.

Comment 4

[Hermann Schwab]

confirming, Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.8a2) Gecko/20040619

using the slider in the scrollbars, the scroll is perfectly synchronized,
but using the arrows at the ends of the scrollbars, the one which is activated
scrolls smoothly, the other which should be synced, is jumping, about
one-and-a-half lines if scrolling vertically, or about two characters if
scrolled horizontally. Thats a rough guess, can´t be seen so exactly.
This happens in all directions, up, down, left, right.
Seen on a slow Celeron 333, but scrolling using the sliders was fast and
perfectly synced, only scrolling using the arrows at the end of the scrollbars
was showing this bug.

Comment 5

[Gérard Talbot]

(In reply to comment #4)
 the one which is activated
> scrolls smoothly, the other which should be synced, is jumping, about
> one-and-a-half lines if scrolling vertically, or about two characters if
> scrolled horizontally. 

Ok, I also notice the behavior described in comment #4 when and only when smooth
scrolling is activated
(Edit/Preferences.../Appearance/Use smooth scrolling)
otherwise I don't notice it and get the expected results.
This is important to explicit and this differential behavior is consistent here.

Comment 6

[Pablo]

Confirmed the behaviour of <a
href="http://bugzilla.mozilla.org/show_bug.cgi?id=247531#c4">comment #5</a> in
Mozilla FireFox 0.9 (Win XP SP1 SPA).

Comment 7

[Boris Zbarsky [:bzbarsky]]

So is the issue that the intermediate smooth-scroll stages don't fire onscroll
events?  Sounds like it to me...

Comment 8

[Firefox Bug Husbandry Bot]

https://bugzilla.mozilla.org/show_bug.cgi?id=1472046

Move all DOM bugs that haven't been updated in more than 3 years and has no one currently assigned to P5.

If you have questions, please contact :mdaly.