1722398 - ASSERTION: Creating widget for MenuPopupFrame with children: '!mGeneratedChildren && !PrincipalChildList().FirstChild()', file layout/xul/nsMenuPopupFrame.cpp:269

Status: NEW

(Core :: XUL, defect)

Description

[Daniel Holbert [:dholbert]]

Attachment: assert-addon.zip (used in STR)

STR:

1. Start a debug build of mozilla-central.
2. Install attached add-on (visit about:debugging, choose "install temporary add-on", and select a local copy of assert-addon.zip, which I'm including here as an attachment)
3. Click the newly-added puzzle-piece icon on your toolbar.
4. Click elsewhere to dismiss the popup.

ACTUAL RESULTS:
Your terminal shows something like:

[Parent 84547, Main Thread] ###!!! ASSERTION: Creating widget for MenuPopupFrame with children: '!mGeneratedChildren && !PrincipalChildList().FirstChild()', file layout/xul/nsMenuPopupFrame.cpp:269

EXPECTED RESULTS:
No such assert.

This happens regardless of whether fission is enabled, i.e. this isn't a fission-related thing.

Side note: given that this is in XUL code, and seems harmless (nothing actually breaks as far as I can tell), I'm not sure we'll bother to fix it; I'm mostly filing it to document the fact that this is a known issue, since at first I was worried that it might be a fission-specific thing [but it's not].

Comment 1

[Daniel Holbert [:dholbert]]

Note, the attached addon is just a trivial add-on with a toolbar button that triggers an extremely-basic popup html document, which just has a string of text.