1226915 - [e10s] It's possible to accidentally scroll the page with expanded <select>, and detach it from its options

Status: RESOLVED FIXED

(Core :: Layout: Form Controls, defect, P3)

Description

[arni2033]

Attachment: testcase 1 - [e10s] It's possible to accidentally scroll the page with expanded select, and detach it from its options.html

>>>   My Info:   Win7_64, Nightly 45, 32bit, ID 20151119030404
STR:
1. Open attached "testcase 1"
2. Move mouse pointer over <select>, press left mouse button (don't release it)
3. Move mouse pointer over option "# 10  ", then scroll down using mousewheel

Result:       
 The page was scrolled, and <select>'s list of options is detached from <select> itself
 This is very similar to bug 982121

Expectations: 
 1) <select>'s list of options should never be detached from <select>
 2) Page shouldn't scroll when mouse is placed over a scrollable <option>s list

Note:
 I experienced it on Bugzilla a while ago.
 "Do not release left mouse button" is a common Windows mechanism that I often use. It allows users to
 open menu, then move mouse over the desired menu item and select it - with 1 mousedown and 1 mouseup

Comment 1

[Karla Merza [Away. Please needinfo? Brindusa Tot[:brindusat] ]]

User Agent 	Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:46.0) Gecko/20100101 Firefox/46.0
Build ID 	20160204004009

Tested on Windows 7 x64 with the Aurora 46.0a2 build. I can reproduce the problem.

Comment 3

[Neil Deakin]

OK, so this is hard to reproduce but it happens if you hold the left mouse down and use the scrollwheel at the same time. It looks like the mousewheel event is not being retargetted to the popup properly.

Comment 4

[Neil Deakin]

This is the same cause as 1159301 and the patch there fixes this bug.

Comment 5

[arni2033]

(In reply to Neil Deakin from comment #3)
> OK, so this is hard to reproduce but it happens
> yes → irrelevant

It happens quite often when I try to select an option from long drop-down list on Bugzilla using standard mechanism "pull, then release left mouse button to select an option in one click".
This bug hasn't come "our of nowhere", I'm quite surprised that you haven't immediately recognized functionality I was trying to use (and failed) in scenario from comment 0.

Comment 6

[Neil Deakin]

This should now be fixed.