Is there a mechanism to prevent the window shadow from overflowing the container ViewSize?
Because from what I see, when you call window.maximize(), scrollbars appear.

There's the method fitContainer that calls container.getViewSize() and applies the result to its own size. However, Ext.dom.Underlay.realign() calculates its size as [width + offsets.w,height + offsets.h] . I don't see any check that this would overflow the container.