In current beta, dev and canary channels of Google Chrome my ExtJS 4.1b2 application breaks in a various places (it's a viewport+tabpanel+bunch of border layouts): width is set to 0px on most of the elements.
It works perfect in Google Chrome Stable.
I'm currently experiencing exactly this, for exactly this structure of application: Viewport, tabpanel, border layouts inside the tab panel, on Chrome Stable. It started a few days ago for us on an app that had been running fine on beta2 for a while. Did you ever find out anything further on this?