1513522 - [Win] Black flash instead of button+icon on hover on RDM/DevTools buttons

Status: RESOLVED DUPLICATE of bug 1518802

(DevTools :: Responsive Design Mode, defect, P3)

Description

[Cristian Fogel [:cfogel]]

Attachment: devTools_Flash.png

[Affected versions]:
- 66.0a1 (2018-12-11), 65.0a1(2018-11-28)

[Affected platforms]:
- Win10x64, Win7;

[Steps to reproduce]:
1. Launch Firefox, open devTools, enable RDM mode;
2. Between the 4 buttons in the topRDM_menu) section, hover over each;
3. Click on the Enable Touch simulation button;
4. Click on the Cogwheel button;

Issue can be noticed for the following cases:
- hover over the RDM button(before enabling the mode);
- hover over the settings button;
- hover between the Snapshot and Cogwheel as well; the black square appearing for the other icon, not the one clicked on; 
- hover over and off the Touch simulation toggle button causes the issue;
- hovering over the >> button displayed when devTools tabs need to be hidden;

[Expected result]:
- buttons have only the hover/active/normal/clicked state styling displayed.

[Actual result]:
- the button's background and icon "flash" to black for ~1 second;

[Regression range]:
- bug 1504065 appears to have introduced this issue;

[Additional notes]:
- attached image with the issue for one of the buttons;
- 65.0b4 does not appear to be affected, currently it's still on the nightly branch;

Comment 1

[Cristian Fogel [:cfogel]]

Hey there Hiroyuki, mind taking a look at this? 

Also ... on Ubuntu(18.04) the hover effect appears to flash as well (grey not black) with just steps 3+4 reckon it's something that can be fixed here or should we open a new bug for it?
Thank you!

Comment 2

[Hiroyuki Ikezoe (:hiro)]

(In reply to Cristi Fogel [:cfogel] from comment #0)
> Created attachment 9030686 [details]
> devTools_Flash.png
> 
> [Affected versions]:
> - 66.0a1 (2018-12-11), 65.0a1(2018-11-28)

Which is the exact revision of the 66.0a1?  This issue might be solved by bug 1512754.

Comment 3

[Cristian Fogel [:cfogel]]

Build id: 20181212051241 and today's 20181212215507 are both affected still.

Comment 4

[Hiroyuki Ikezoe (:hiro)]

Thanks.  I will take a look.

Comment 5

[Hiroyuki Ikezoe (:hiro)]

I can't reproduce the issue at all on Linux.  It would be greatly appreciated if someone provides a reduced test case.

Comment 6

[Cristian Fogel [:cfogel]]

For Linux it's limited to the scenario in the initial comment(FFX 65.0a1 - 20181128100125 and FFX 66.0a1 - 20181212215507) 
- enable Touch Simulation;
- disable Touch simulation;
- click on the Cogwheel;

Comment 7

[Hiroyuki Ikezoe (:hiro)]

Note that the feature caused this issue is prefed off on beta an release channels.

Comment 10

[Hiroyuki Ikezoe (:hiro)]

It turns out this is a duplicate of bug 1518802.