Focus lost when toolbar Source button is used

When the toolbar Source button is pressed, focus is removed from CK Editor. With FF3 it is caught by the browser and tabbing moves through the URL bar, etc.
I need focus to be placed back into the editor so test scripts can inject test data into the editor.

Problem initially seen with v3.5.2 integrated into a web application, but online demo pages are exactly the same.
Also can see same behaviour in nightly build demo pages; so the recent change sets on editingblock / plugin.js haven't affected focus (main changeset is 6478).

I'm trying to work out how to force focus back into the editing area.
I've managed to over-ride setMode() and was hoping to insert some code to place focus at the end of the method, after the made change had taken place.

I've tried editor.focus() and editor.forceNextSelectionCheck() - no change...
The problem is that editor.getSelection is null; it is being cleared by the mode change. I've confirmed the selection contains meaningful content before the mode is changed.

I can create a new selection, but I've not worked out how to assign it back to the editor.

var selection = new CKEDITOR.dom.selection(editor.element.getDocument());

It looks like it ought to be easy!
I've had a good search in the development TRACS system, CK Editor documentation, this Forum and using Google - they turned up nothing relevant.
Any suggestions ???????

Thanks in advance - Duncan

P.S. We are currently using v2.6.1 (other problems prevented upgrade to more recent versions of v2). I've checked that our OEM license is valid for CK Editor, but our support needs upgrading - this is going to take at least a week because it is the end of the financial year. Ideally I'd like to get this sorted out sooner than that. I feel there has to be something simple I've missed!