1377665 - When the browser is running slowly, clicking on a link and then holding down Ctrl executes a Ctrl+click

Status: UNCONFIRMED

(Core :: DOM: UI Events & Focus Handling, defect, P3)

Description

[Paul]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0
Build ID: 20170612121707

Steps to reproduce:

Leave Firefox running for a few days/weeks so that its response is a little slow. (This doesn't require major load or jank, just enough to delay actions by 50-100ms.) Click a link, and immediately after releasing the mouse/touchpad button or touchscreen, hold down the Ctrl key, as you would if you were about to e.g. Ctrl+Tab.


Actual results:

The click is interpreted as Ctrl+click, even though Ctrl wasn't pressed at any time during the click.


Expected results:

The click should be interpreted as a click, and holding down Ctrl should modify whatever action is done afterwards.

Comment 1

[Andrew Overholt [:overholt]]

Some sort of event coalescing?

Comment 2

[Ming-Chou Shih [:stone]]

On Linux, we get and calculate modifier states from the gtk callback of signal 'button-press-event'.

Comment 3

[Andrew Overholt [:overholt]]

(In reply to Paul from comment #0)
> 
> Leave Firefox running for a few days/weeks so that its response is a little
> slow.

Does this happen regularly for you? I'd be interested in exploring root causes a bit more.

Comment 4

[Paul]

Actually yes, just tested with a clean profile and freshly started browser, and this bug still manifests whenever Ctrl is pressed within ~250ms of clicking a link. Very weird.

Comment 5

[Olli Pettay [:smaug][[e-mail]]]

One can still trigger this if mouseup and ctrl press happen around the same time and I seem to get same behavior on other apps too
(like Chrome) on linux.