I'm afraid I'm on Mr. Hanson's side here.
My example is the Address Book Window. Address Books are listed in upper left pane; address entries in the pane below; and address details in right pane.
Bring up the Address Book window
Select a Book
Select an entry - it is NOT selected
Click it again - NOW it's selected
Now that you are in the Window, going back and forth between Books and Entries selects with a single click.
A non-Pegasus example of focus switching:
Have browser open and in focus, sharing screen with a text editor, word processor, whatever (so you can see both).
With a single mouse click-and-sweep, select text in other app, a url maybe, or anything.
Note that focus switches AND text selection occurs.
Also, with text selected in other app, switch to browser via click.
Now right-click selected text in other app - context menu appears - NO second click needed.
This says focus-switching and an operation action can and should be done with one mouse operation. If focus-switching is handled by it's own listener, that listener should then call/allow operation listener to have control. My opinion, anyway.
Chryasor