1179188 - When Firefox lags, text characters typed during the lag are repeatedly output when typing thereafter until it is restarted

Status: VERIFIED INCOMPLETE

(Firefox :: Untriaged, defect)

Description

[ruth.cheesley]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0
Build ID: 20150511103303

Steps to reproduce:

I have this problem whenever I experience lag in Firefox and I'm typing at the time.  Examples can be: 
- Loading a new tab and starting to type an email
- Typing a message in one tab while something in another tab causes the browser to lag (e.g. a slow loading page, video etc)


Actual results:

If I start typing, then it lags, it seems to 'remember' some of the characters I was typing.

When the lag has passed and I continue typing, those characters keep getting output in the middle of the text I'm writing, at regular intervals.

So, if I was typing:

"It's a nice day today"

and it lagged on "nice d"

Then when I am typing 

"But it's really rather warm"

it appears as 

"But it's nice dreally rather warm"

I have this happen frequently and this affects all Firefox tabs, even if I close them and open, it's still happening.  Other applications are fine - I can type the text into Kate and copy/paste into wherever I want the text to go, and it does not include the random chunks of text.

The only way I've found to get around this is to restart firefox, thereafter the problem resolves until the next lag.  Sometimes this can be weeks between it happening, sometimes hours.

The most common place I find it happen is Gmail, where I am writing an email in a compose window.  

I use Kubuntu with Firefox 38 and I had this problem on 14.04, 14.10 and still on 15.04 so it's been long standing, but haven't ever reported it.

I have never had this problem on my phone with Firefox Beta.


Expected results:

The text I type should not have random characters being inserted!

Comment 1

[ruth.cheesley]

Here's an example in action:

Apologies for the late r sponse, rwas up late

Comment 2

[Virtual_ManPL [:Virtual] 🇵🇱 - (please needinfo? me - so I will see your comment/message/reply/question/etc.)]

Hello

Can you reproduce the issue in Safe Mode[1]?
If yes and you can reproduce the issue in Safe Mode,
can you still reproduce it even with clean new fresh profile without any addons (extensions and plugins)[2]?

You can also try a standard troubleshoot and diagnose procedure[3].



[1] = https://support.mozilla.org/kb/troubleshoot-firefox-issues-using-safe-mode
[2] = https://support.mozilla.org/kb/refresh-firefox-reset-add-ons-and-settings
[3] = https://support.mozilla.org/kb/troubleshoot-and-diagnose-firefox-problems