For the case where I want to center some text, I want the title to be left justified. You example is the opposite: title is centered, other text is left justified.
This bug also affects cases where you want to right justify text. For example, if I want a left justified title, but want to add a right justified text. The text would need to be specified in the items config, but then it would be rendered before the title. Thus the title also has to be specified in the items config, but then the empty title automatically kicks in. This makes the right justified text appear to be centered. Example: http://jsfiddle.net/KQTfP/2/
The panel header is a fairly unique component, similar the paging toolbar. It can accept items, but by default they are mostly configured externally by another component. As such, it makes it difficult to provide a reasonable level of flexibility without adding significant complication.
As such, your best bet is to override initComponent and manipulate the items collection:
// have at it!
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