1163652 - Menu panel always shows a scroll bar when used at certain UI zoom levels

Status: RESOLVED WORKSFORME

(Firefox :: Toolbars and Customization, defect, P3)

Description

[(Currently slow to respond) Philipp Sackl [:phlsa] (Firefox UX) please use needinfo]

Attachment: screenshot of the bug

The main menu panel on Windows 10 always shows a scroll bar. This is made even worse by the fact that the scroll bar appears after the panel has opened, giving it an extra shake.

The scroll bar should only be shown when it is actually needed.

Comment 1

[Mark Hammond [:markh] [:mhammond]]

Attachment: markh-win10-menu.png

WFM on build 10074 :(

Comment 2

[(Currently slow to respond) Philipp Sackl [:phlsa] (Firefox UX) please use needinfo]

Just tested this in a VM on the Mac and it works there, but I can reliably reproduce it on a Dell XPS13. Is it possible that it's related to touch capabilities?

Comment 3

[Mark Hammond [:markh] [:mhammond]]

(In reply to Philipp Sackl [:phlsa] please use needinfo from comment #2)
> Just tested this in a VM on the Mac and it works there, but I can reliably
> reproduce it on a Dell XPS13. Is it possible that it's related to touch
> capabilities?

I saw a similar bug on Windows 7 in the past when the "text zoom" (ie, "make text smaller or later" or "dpi") was not the default. While I tried to play with a few versions of this and still failed to reproduce it, it might be worthwhile recording what parameters the dell has for all screen or display options you can find and see if applying them to the VM makes it reproduce.

Comment 4

[(Currently slow to respond) Philipp Sackl [:phlsa] (Firefox UX) please use needinfo]

You're right Mark, it seems to be related to UI scaling.
When I set my laptop to 100% or 200% scaling, the scroll bar is hidden as it should be. Setting it to 250% (recommended for this screen) causes the scroll bar to show up.

This is actually good news, since it takes some of the pressure out of this bug.

Comment 5

[Mark Hammond [:markh] [:mhammond]]

the other "good" news may be that it reproduces on more than win10?

Comment 6

[Jared Wein [:jaws] (please needinfo? me)]

I tried various values of layout.css.devPixelsPerPx and couldn't reproduce this on my Windows 8.1 install. Did you have a value that worked for you that maybe I could try with?

My guess is that this is happening due to a rounding error in our calculation for the menu size. If we added a few extra pixels to the size that would effectively fix this without much noticeable difference.

Comment 7

[Mark Hammond [:markh] [:mhammond]]

(In reply to Jared Wein [:jaws] (please needinfo? me) from comment #6)
> If we added a few extra pixels to the size
> that would effectively fix this without much noticeable difference.

IIRC that's how we fixed a similar bug in that past (that I now can't find for some reason, but I'm sure it existed as I saw it then) - but this time I can't find a value to trigger it. Hopefully Phillip can tell you exactly how his is configured.

Comment 8

[:Gijs (out for now; he/him)]

Philipp, can you make sure you bring this machine to Whistler if providing more details before then that allow us to repro is not possible? Thanks!

Comment 9

[(Currently slow to respond) Philipp Sackl [:phlsa] (Firefox UX) please use needinfo]

Hm, interestingly enough I can't reproduce it anymore (not in Nightly, not in Release) :/
Perhaps a Windows update changed something? I'm on 10130 now.

Comment 10

[Justin Dolske [:Dolske]]

Can't reproduce, no new reports. Please reopen if we see it again!