Comment 2 for bug 783595

I see 3 issues that need fixing:
1. When the overlay is shown, focus must be given to the first control
2. Users can leave the overlay, but the tab key should cycle through the overlay.
3. the accordion widget does not recognise the "enter" key to toggle state.

1 and 2 might be solved by changing the subscription overlay to extend lp's PrettyOverlay which handles tabs and seems to focus correctly. Otherwise _getTabNodes and _handleTab are needed. These methods also illustrate how to focus elements and capture keypresses. The accodion will need extending or patching to understand key presses.