812817 - "ASSERTION: Invalid display item type!" with Ctrl+Tab preview of about:memory

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Jesse Ruderman]

Attachment: stack+

1. Create a profile with:
     user_pref("browser.ctrlTab.previews", true);
2. Launch Firefox
3. Ensure you have exactly one tab open
4. ⌘T, about:memory, Enter
5. ⌘T, about:memory, Enter
6. Ctrl+Tab

Result:

###!!! ASSERTION: Invalid display item type!: 'type > TYPE_ZERO && type < TYPE_MAX', file nsDisplayItemTypes.h, line 69

This assertion is part of code added in bug 798964.  When the assertion fails, type is nsDisplayItem::TYPE_ZERO.

Comment 1

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

Those STR do not work for me on Windows. Mac-only?

Comment 2

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

FrameLayerBuilder::BuildContainerLayerFor can pass 0 as the display item key when constructing a root layer. So if the root frame of the root document has a background image, we'll hit this assertion. I suspect that's what's happening here.

Comment 3

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

Attachment: fix

Comment 4

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

https://hg.mozilla.org/integration/mozilla-inbound/rev/52473aa84e9d

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/52473aa84e9d