Here's the test case:
Bad http://www.cb1inc.com/files/BorderContainerBad.html
Fixed http://www.cb1inc.com/files/BorderContainerFixed.html
This just fixes the BorderContainer?'s splitter. I'm sure there are other widgets that are affected such as TabContainers? inside a BorderContainer? (afaik just the center region) don't resize when the browser is resized. But I'm sure that's probably another ticket...