873010 - Artifacts around small overlay scrollbars in select boxes

Status: VERIFIED FIXED

(Core :: Widget: Cocoa, defect)

Description

[Markus Stange [:mstange]]

Attachment: wip

Testcase: The "Projects" list box on https://bugreports.qt-project.org/secure/IssueNavigator.jspa

This is a scrollbar in a <select> list box, which is marked as small, which returns kSmallScrollbarThumbMinSize for the thumb's GetMinimumWidgetSize. But overlay scrollbars draw the thumb at least 26 pixels long, so the drawing doesn't hit the layout box, so the invalidations are off.

Here's a patch that fixes the minsize and tweaks scrollbar metrics for small scrollbars.

Comment 1

[André Reinald]

I'm not sure what is wrong with the <select> list boxes from that page, to spohl and me their behavior looked fine. Can you please confirm us what's wrong?

Comment 2

[Markus Stange [:mstange]]

Sorry, that was a very rushed bug report.

I see the artifacts in this nightly on 10.8.3:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20130518 Firefox/24.0

Video: http://dl.dropboxusercontent.com/u/2901861/Screenshots/smallscrollbarsartifacts.webm

An alternative testcase is the Component listbox on https://bugzilla.mozilla.org/enter_bug.cgi?product=Core

Comment 3

[André Reinald]

With similar systems (my Nightly is one day newer only) we can't reproduce the bug. Both of us have MBPs Retina. Could the HiDPI screen make a difference ? Maybe we find an external LoDPI monitor to connect at office tomorrow so we can check.

Comment 4

[Markus Stange [:mstange]]

Good call, that's the reason. I've just tested in HiDPI mode and don't see the bug there.

Comment 5

[Markus Stange [:mstange]]

Comment on attachment 750398 [details] [diff] [review]
wip

The only part from this patch which is actually required to fix this bug is this:
-static const int32_t kSmallScrollbarThumbMinSize = 19;
+static const int32_t kSmallScrollbarThumbMinSize = 26;
(It also needs a test fix in widget/tests/test_bug485118.xul.)

Making small scrollbars actually look smaller than regular ones should happen in a different bug.

I'm not sure if we really should set kSmallScrollbarThumbMinSize to 26 unconditionally. For 10.6-style scrollbars and HiDPI 10.7-style scrollbars, 19 seems to work fine, so maybe we should differentiate between these cases. But it's probably not worth it.

Comment 6

[André Reinald]

Attachment: Change kSmallScrollbarThumbMinSize to 26

As per Markus suggestions, this small change is enough to fix the artifacts.

Opened bug 874570 as a follow-up for the appearance change.

Comment 7

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/ff126a7cf2ca

Comment 8

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/ff126a7cf2ca

Comment 9

[Stephen A Pohl [:spohl]]

Comment on attachment 752325 [details] [diff] [review]
Change kSmallScrollbarThumbMinSize to 26

[Approval Request Comment]
Bug caused by (feature/regressing bug #): Bug 636564
User impact if declined: Artifacts around small overlay scrollbars in select boxes
Testing completed (on m-c, etc.): Has been on m-c for several days and testing shows that this is fixed.
Risk to taking this patch (and alternatives if risky): minor
String or IDL/UUID changes made by this patch: none

Comment 10

[Stephen A Pohl [:spohl]]

Requesting checkin for aurora.

Comment 11

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/6c02abf3f2f9

Comment 12

[Samvedana (:Samvedana)]

Can you please provide detail steps to test this? So, I can verify this on FX 23 and 24.

Comment 13

[Stephen A Pohl [:spohl]]

STR:
1. Disable HiDPI mode in about:config by setting gfx.hidpi.enabled to 0.
2. Restart browser.
3. Go to https://bugzilla.mozilla.org/enter_bug.cgi?product=Core
4. Scroll vertically in the "Component" or "Version" list box.

Expected:
No artifacts like the ones shown in this screencast:
http://dl.dropboxusercontent.com/u/2901861/Screenshots/smallscrollbarsartifacts.webm

The scrollbars should display normally.

Comment 14

[u279076]

(In reply to Stephen Pohl [:spohl] from comment #13)
> STR:
> 1. Disable HiDPI mode in about:config by setting gfx.hidpi.enabled to 0.

Does this require a Retina Mac?

Comment 15

[Stephen A Pohl [:spohl]]

(In reply to Anthony Hughes, Mozilla QA (:ashughes) from comment #14)
> (In reply to Stephen Pohl [:spohl] from comment #13)
> > STR:
> > 1. Disable HiDPI mode in about:config by setting gfx.hidpi.enabled to 0.
> 
> Does this require a Retina Mac?

No. A non-retina Mac or a Mac with HiDPI turned off in about:config will do.

Comment 16

[Samvedana (:Samvedana)]

User Agent :Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:23.0) Gecko/20100101 
Firefox/23.0
Build ID: 20130711122148

Tested on Firefox 23 B5 on MAC 10.8 OS, The scrollbars display normally.

User Agent :Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20130712 Firefox/24.0
Build ID: 20130712004003

Tested using Firefox 24 latest Aurora on MAC 10.8 OS, The scrollbars display normally.

Comment 17

[Samvedana (:Samvedana)]

User Agent : Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:23.0) Gecko/20100101 Firefox/23.0
Build ID: 20130715155216

User Agent : Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:25.0) Gecko/20130718 Firefox/25.0
Build ID: 20130718030201

User Agent : Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:24.0) Gecko/20130718 Firefox/24.0
Build ID:  20130718004004

Tested this on latest nightly, Aurora and FX 23 B6 release. I am getting expected result for all above builds. I don't see any issues of scrollbars in select boxes.