Stephan Stahl wrote:

>>>Now try doing the same thing but using C-x 5 o to switch the frames will
>>>cause the popup to work just fine.  Does C-x 5 o some thing special
>>>compared to Alt-tab?
>>>
>>>      
>>>
>>It gives focus to an Emacs window. The same is seen if you switch focus
>>by clicking on the title bar vs in the text area.
>>    
>>
>
>But C-x 5 2 seems to do this too.
>
My point was that Alt-tab does not.