[webkit-dev] Focus Crash Relating to MathML

Alex Milowski alex at milowski.org
Sat Oct 16 15:38:04 PDT 2010

If anyone has any ideas of this bug:


I'd appreciate the help.

Basically, when the MathML is wrapped in an anchor parent, the focus
event causes a crash at:

ASSERTION FAILED: !renderer()->needsLayout()
(/Users/alex/workspace/WebKit/WebCore/dom/Node.cpp:793 virtual bool
WebCore::Node::isFocusable() const)

The node in question is the anchor itself.  It is marked as needed
layout, which I
presume is coming from the MathML rendering objects, but all the
children rendering
objects are marked as not needing layout.

If you try out the example attached to the bug, just click on the tiny "x"
in the example.  That will cause the crash.

My guess is that this is related to a larger issue of layout not propagating
correctly with MathML.  In certain situations, I've seen MathML layout
overflow containers and then a simple window resize or similar user
action will cause everything, including the MathML, to reflow correctly.  I
haven't narrowed down specific cases of this problem quite yet.

--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language

Bertrand Russell in a footnote of Principles of Mathematics

More information about the webkit-dev mailing list