The nsIWebBrowserChromeFocus is implemented by the same object as the
 nsIEmbeddingSiteWindow. It represents the focus up-calls from mozilla
 to the embedding chrome. See mozilla bug #70224 for gratuitous info.

 @status FROZEN
[scriptable, uuid(d2206418-1dd1-11b2-8e55-acddcd2bcfb8)]
interface nsIWebBrowserChromeFocus : nsISupports

Methods

 Set the focus at the next focusable element in the chrome.
void focusNextElement() 
 Set the focus at the previous focusable element in the chrome.
void focusPrevElement()