Bug 150029 – Incorrect initial rendering with Tab characters and white-space:pre/padding-left

• Status: RESOLVED
• Resolution: WORKSFORME
• Component: Layout and Rendering

[Adam Roben (:aroben)]

Created attachment 262887 [details]
test file to demonstrate the bug

Elements with padding-left and white-space:pre that contain a Tab character render differently depending on whether the element has any element children.

To reproduce:

1. Open the attached tab-test.html
2. See that the two pairs of example lines are not left-aligned with each other
3. Select the text in the page

Now the example lines *are* left-aligned with each other. See attached GIF for an animation demonstrating the behavior.

The only difference between the lines in each pair is that one of them contains a <span> and the other does not.

This affects code rendering on github.com. This particular example was reduced from https://github.com/phonyphonecall/mb-gnu-docker-mgr/blob/7a8e67de3389a3ebf8f82e2d4ceab2ccedb5d360/mb-gnu-docker-mgr.go

[Adam Roben (:aroben)]

Created attachment 262888 [details]
GIF showing the bug

[Adam Roben (:aroben)]

I've been testing with Safari 9 on OS X 10.11. The bug does not occur in Chrome 45 or Firefox 41.

[alan]

This works fine with r191029. It must have been fixed by one of my simple line layout patches. 
(when the text is selected, we switch bail out of simple line layout. Different text positions (selected vs non-selected text) is an indication of a simple line layout bug. )

[Adam Roben (:aroben)]

Sorry for not testing in the nightly before filing this!

I just tried to verify in the latest nightly build (r191040), but the bug still reproduced. But I'm actually not sure the nightly WebKit was being used (maybe due to System Integrity Protection?); navigator.userAgent didn't mention the nightly build at all.

Is there something special I need to do to use nightly builds on El Capitan?

[alan]

(In reply to comment #4)
> Sorry for not testing in the nightly before filing this!
> 
> I just tried to verify in the latest nightly build (r191040), but the bug
> still reproduced. But I'm actually not sure the nightly WebKit was being
> used (maybe due to System Integrity Protection?); navigator.userAgent didn't
> mention the nightly build at all.
> 
> Is there something special I need to do to use nightly builds on El Capitan?
Not that I know of. (cc: ddkilzer) I downloaded the nightly and the attached test case works fine with it. (see attachment)

[alan]

Created attachment 263077 [details]
Verified on nightly

[Adam Roben (:aroben)]

> Is there something special I need to do to use nightly builds on El Capitan?

I filed bug 150180 about this.