658427 - Delay on mouse-over of hyper-links in FF4

Status: NEW

(Firefox :: General, defect)

Description

[James Haigh]

User-Agent:       Mozilla/5.0 (X11; Linux i686; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Build Identifier: Mozilla/5.0 (X11; Linux i686; rv:2.0.1) Gecko/20100101 Firefox/4.0.1

When the mouse is moved to hover over a link, the pop-up in the bottom-left showing the destination address does not appear immediately.

Note that there is no delay when leaving the the mouse-over; when the mouse is moved away the pop-up disappears immediately.

This annoying when mousing-over several near-by links. I have to wait between each link and there is a general feel of unresponsiveness that was not present in earlier versions of FF.

Reproducible: Always

Steps to Reproduce:
1. Mouse-over a link.

Actual Results:  
There was a delay.

Expected Results:  
Immediate response.

Comment 1

[Thomas Ahlblom]

WFM:
Mozilla/5.0 (X11; Linux x86_64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Mozilla/5.0 (X11; Linux x86_64; rv:6.0a1) Gecko/20110519 Firefox/6.0a1

Does the issue still occur if you start Firefox in Safe Mode?
https://support.mozilla.com/en-US/kb/Safe+Mode

How about with a new, empty profile?
https://support.mozilla.com/en-US/kb/Basic+Troubleshooting#w_8-make-a-new-profile

Comment 2

[:aceman]

How long is the delay you see? Tenth of a second? 1 second? 10 seconds?

Comment 3

[James Haigh]

(In reply to comment #2)
> How long is the delay you see? Tenth of a second? 1 second? 10 seconds?

Varies hugely, but often a few seconds. With more experimentation, it appears that unless the pointer is absolutely still to the pixel, the delay continues. Many pointing devices are not pixel accurate. If the pointer continues to move, the delay can be indefinite.

The expected result would be that the pop-up shows immediately as soon as the pointer crosses the bounding box of the link.

Comment 4

[James Haigh]

(In reply to comment #1)
...
> Does the issue still occur if you start Firefox in Safe Mode?

Yes. I can also confirm it for Mac OS X Snow Leopard.

Comment 5

[:aceman]

You see it on Linux (original report) and also Mac OS X? Is it on the same machine? If yes, what is the model of your mouse?

Comment 6

[James Haigh]

(In reply to comment #5)
> You see it on Linux (original report) and also Mac OS X? Is it on the same
> machine? If yes, what is the model of your mouse?

No. 3 different machines:

 * Dell Latitude (Ubuntu 11.04)
     - pointing stick
     - touchpad
 * Thinkpad (Ubuntu 11.04)
     - pointing stick
 * Macbook Pro (not mine)
     - trackpad (or whatever they call it)

The behaviour I described in comment #3 is consistent for all the pointing devices. The delay is worst (often more than 5 seconds) for the pointing sticks (my preferred pointing device), as they often wonder a few pixels when the finger is resting on them. The delay is reduced for all pointing devices by completely letting go of the device when over the link, but this is still annoying.

Comment 7

[:aceman]

Interesting. Could you try it with a normal mouse connected to any of those machines?

I assume by "wonder" you mean wobble/jitter. With this information I can confirm the bug on my linux, also on FF 5.0a2. I can simulate the jittering of mouse cursor by hand and really the popup with the URL doesn't appear until I stop doing it.

I'll move the bug to a better component and maybe the appropriate developer enlightens us if this is the intentional behaviour.

However, aren't your sticks/touchpads too sensitive? Or do you possibly have problem to keep your finger still? Then this could be a tip for accessibility enhancement of FF.

Comment 8

[:aceman]

Nevertheless, can you also try it in other browsers? How do they handle this?

Comment 9

[James Haigh]

(In reply to comment #7)
> Interesting. Could you try it with a normal mouse connected to any of those
> machines?

No. I don't have one with me. I let someone borrow my mouse months ago.

I find that most cheap optical mice have more jitter than touchpads anyway, even on good surfaces.

> 
> I assume by "wonder" you mean wobble/jitter. With this information I can
> confirm the bug on my linux, also on FF 5.0a2. I can simulate the jittering
> of mouse cursor by hand and really the popup with the URL doesn't appear
> until I stop doing it.

By wonder I mean something more consistent than wobble or jitter. Pointing sticks tend to give the pointer a very smooth motion.

> 
> I'll move the bug to a better component and maybe the appropriate developer
> enlightens us if this is the intentional behaviour.

If this is intentional does that mean this is not a bug and won't be fixed? :-(

I think it probably is intentional. Surely extra logic is required to tell when the pointer stops, and that can't have been done by accident. Though it should make easy to fix, simply remove the extra logic.

> 
> However, aren't your sticks/touchpads too sensitive? Or do you possibly have
> problem to keep your finger still? Then this could be a tip for
> accessibility enhancement of FF.

The delay tends to be less than a second now I know to stop the pointer, but it still feels sluggish unlike the rest of Firefox 4 (which I appreciate is very fast indeed). The general tendency that people have when something doesn't respond is to wave or move the pointer over it. In this case it has the opposite effect. Also, some people may not be able to keep the pointer still due to most common cheap pointing devices being pixel inaccurate, or due to disability.

(In reply to comment #8)
> Nevertheless, can you also try it in other browsers? How do they handle this?

Chromium also has these pop-ups. They appear immediately when the pointer enters the bounding box of the link, and generally has a more responsive feel.

Comment 10

[:aceman]

Maybe it was done as a performance enhancement, to not show the bar for 100s of links while you move the mouse across a page when you clearly are not interested in them. When you stop the mouse, you are interested and the link shows up.
Thanks for your answers, I have marked your bug as valid.

You said the delay does not happen on Firefox 3.6. There the URL shows in the statusbar. The showing of link URL was rewritten for Firefox 4, maybe this is just an omission and not intentional.

Comment 11

[James Haigh]

(In reply to comment #10)
> Maybe it was done as a performance enhancement, to not show the bar for 100s
> of links while you move the mouse across a page when you clearly are not
> interested in them. When you stop the mouse, you are interested and the link
> shows up.
> Thanks for your answers, I have marked your bug as valid.

Thank you.

With regards to performance, I loaded Gmail on Chromium on my fairly modest Dell Latitude D620. The inbox is a page full of links. I did not notice any bad performance when waving the pointer across all the links. Surely the performance hit is negligible.

I did however notice a feature that serves the same purpose if this bug actually /was/ intended as a performance enhancement. Although in Chromium the pop-up appears instantly, it waits about half a second before disappearing. This means that if you move the pointer over links that are not adjacent, they will still reuse the existing pop-up, so the pop-up is not flickering (appear disappear appear disappear...). This would have the same small performance improvement without the disadvantages of the current behaviour.

I cannot fault Chromium's link preview pop-up behaviour.

Comment 12

[Alex Limi (:limi) — Firefox UX Team]

Chromium's behavior as described makes sense.