This error seems not to be caused by your changes but by something in 
the Omnibrowser panes. I have before fixed this error in the old browser 
but it seems Omnibrowser has some other widget than the regular browser...
I observed the error on a older version of Damiens 3.10 dev images and 
I'll see if I can track it down:-)

Karl
<http://lists.squeakfoundation.org/pipermail/squeak-dev/2007-September/date.html#120107> 
<http://lists.squeakfoundation.org/pipermail/squeak-dev/2007-September/author.html#120107> 

> Could you be more specific. The list panes get updated due to the 
> focus rectangle being drawn... Have uploaded a new version of Widgets 
> on SqueakSource that allows "click to focus" which eliminates the 
> redraw for mouse enter (if you like that behaviour, that is!).
> /
> /
>
>     There is a bug in drawing / updating list panes on mouse enter.
>     You see
>     this by enabling Preference debugShowDamage. I have seen this bug
>     before
>     and it is triggered when a morph is added to a owner but it's
>     position
>     is not set and it's therefore added to World topLeft. I'm not sure
>     which
>     morph is causing it here, it could be PluggableListMorph, ScrollPane,
>     LazyListMorph or some other.
>     Drawing bugs slow the feel of the UI down quite a bit.
>
>     Karl
>
>