2019067 - Zoom level of devtools can affect expand on hover rect for vertical tabs

Status: RESOLVED FIXED

(Firefox :: Sidebar, defect, P2)

Description

[Mike Conley (:mconley) (:⚙️)]

Attachment: zoomed-devtools-vtab-bug.mp4

STR:

1. Enable vertical tabs, with expand on hover enabled to true
2. On any page, open up browser devtools (not the Browser Toolbox, the in-page developer tools), via F12
3. With the devtools focused (perhaps by clicking on the text area in the console), increase the zoom level to maximum by holding Ctrl and + (or Cmd and + on macOS)
4. With the devtools zoomed, move the mouse cursor over top of the inspect button in the top left of the devtools

ER:

The vertical tabs should only expand when the vertical tab strip is hovered.

AR:

With a high enough zoom level, just passing over the inspect button's halfway point seems to be enough to trigger it.

See attached video.

Comment 1

[Mike Conley (:mconley) (:⚙️)]

The workaround is to reset the zoom level of the devtools to the default with Ctrl / Cmd + 0

Comment 2

[Nikki Sharpley (:nikkis) (she/her)]

Hi Nicholas. We wondering if you've seen similar issues or have any ideas on a fix for this? Thanks!

Comment 3

[Nicolas Chevobbe [:nchevobbe]]

(In reply to Nikki Sharpley (:nikkis) (she/her) from comment #2)

Hi Nicholas. We wondering if you've seen similar issues or have any ideas on a fix for this? Thanks!

I thought we had something similar in the past, but I can't find a bug that would describe the same situation :/

Comment 4

[Sam Foster [:sfoster] (he/him)]

I'll take a look into this.

Comment 5

[Sam Foster [:sfoster] (he/him)]

It looks like the event.screenX and event.screenY values we get in handleEvent are pre-scaled using the target's devicePixelRatio. In this case, although the currentTarget is the ChromeWindow, the event.target is a devtools inspector element so everything gets scaled by its dpr which is 4 (max zoom level). At this point, subtracting window.mozInnerScreenX doesn't make any sense - these are different coordinate spaces.

Comment 6

[Sam Foster [:sfoster] (he/him)]

Attachment: Bug 2019067 - Re-scale coordinates in MousePosTracker to account for a different target's devicePixelRatio. r?emilio!

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/52f980476bad
https://hg.mozilla.org/integration/autoland/rev/2c34f83e5719
Re-scale coordinates in MousePosTracker to account for a different target's devicePixelRatio. r=emilio,frontend-codestyle-reviewers

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/2c34f83e5719