783106 - OOP + specific set of CSS properties causes text to be invisible

Status: RESOLVED WORKSFORME

(Firefox OS Graveyard :: General, defect)

Description

[Justin Lebar (not reading bugmail)]

STR: Apply the attached patch to Gaia, then run B2G and open the UI test app.  It'll be empty, a black screen.

Now undo the change to apps/system/js/window_manager.js that the patch makes; this will cause the UI test app to run in-process.  Run B2G and open the UI test app again.  It's no longer blank: There's a bunch of links inside.  This is what it should look like.

What's particularly bizarre is that, if you remove the border-bottom-right-radius declaration in the CSS file for #foobar, the text shows up again.  The text also shows up if you remove the font-size declaration for #foobar > li, the text shows up.

The unmodified UI test app exhibits the same behavior; this patch is just an attempt to isolate things a bit.

Huh??

Comment 1

[Justin Lebar (not reading bugmail)]

Attachment: Testcase (patch to Gaia)

Comment 2

[Justin Lebar (not reading bugmail)]

> STR: Apply the attached patch to Gaia, then run B2G and open the UI test app.  It'll be empty, a 
> black screen.

Although the screen appears empty, the text is still there, afaict.  You can click on the invisible links, and the "you're hovering over text" cursor shows up at the right times.

Comment 3

[Chris Jones [:cjones] inactive; ni?/f?/r? if you need me]

We should be able to make this into a reftest.  Most likely the bug is already covered by existing tests that just aren't running ...

Comment 4

[Justin Lebar (not reading bugmail)]

I get the same behavior when I copy this code into the template app -- works in-process, text is invisible (on a white background this time) out-of-process.

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Maybe something to do with cross-process mask layers?

Comment 6

[Justin Lebar (not reading bugmail)]

Attachment: Testcase v2 (patch to Gaia template app)

This is a testcase to the template app, instead of the UI test app.

We've also discovered that the font-size requirement was something of a red herring: The requirement is that the <ul> be long enough to show scrollbars.

Comment 7

[Chris Jones [:cjones] inactive; ni?/f?/r? if you need me]

I thought there was an outside chance this was related to bug 783355, but the testcase works fine in rev 5c730c1f2274 on the otoro.  So that might be a hint for a starting point for a bisect.

Comment 8

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

It sounds like this has the potential to "break the web". It's also affecting various built-in apps. Dave mentioned that this is likely the reason that the "scanning for new media" dialog in the gallery app renders without text when running OOP.

Comment 9

[Nick Cameron [:nrc]]

Can you recreate this on desktop or Android? If you can then I can have look into it. I'm afraid I don't have a b2g setup (if needed I can work that out, but I'd rather avoid that if I can).

Comment 10

[Justin Lebar (not reading bugmail)]

(In reply to Nick Cameron [:nrc] from comment #9)
> Can you recreate this on desktop or Android? If you can then I can have look
> into it. I'm afraid I don't have a b2g setup (if needed I can work that out,
> but I'd rather avoid that if I can).

I can reproduce this on desktop b2g on my Linux box.  (Building desktop b2g requires just a configuration flag in your mozconfig; see https://wiki.mozilla.org/Gaia/Hacking.)

Comment 11

[Nick Cameron [:nrc]]

I have b2g up and running on a mac, but could not reproduce this bug. I applied the patch to the Gaia directory and ran make there and rebuilt b2g for good measure, but did not see any change in the UI test menu. That menu rendered with rounded corners and visible text. (I'm assuming that settings like OOP and accelerated layers are the same on mac as Linux). Any idea for how to reproduce this?

Does the b2g browser use the same OOP architecture as Gaia? Have you been able to reproduce the behaviour on a webpage?

Comment 12

[Justin Lebar (not reading bugmail)]

To be clear, with the "patch to Gaia template app", you need to open the template app, not the UI test app.

The patch does not apply against Gaia tip (rev 9c614e4d25b697b7cc4) because the template app is no longer in the OOP blacklist, but you can safely ignore that patch reject (git apply --reject).

I'm on slow wifi at the moment, so I'll let you know if I can reproduce once everything finishes downloading.

Comment 13

[Justin Lebar (not reading bugmail)]

This works fine for me on my mac.  I can't reproduce the problem anymore, with any of the testcases.

I guess we fixed it?  :-/

Comment 14

[Nick Cameron [:nrc]]

(In reply to Justin Lebar [:jlebar] from comment #13)
> This works fine for me on my mac.  I can't reproduce the problem anymore,
> with any of the testcases.
> 
> I guess we fixed it?  :-/

Hmm, well that was easy, hopefully it will stay fixed.