bug#62032: 28.2; `switch-frame' event exits incremental search

[Farblos]

> This looks related to bug#41338 that is still unfixed.
> But maybe 'ignore is really the right way to fix, this needs testing.

Agreed, but bug#41338 seems to imply that the comment from isearch.el 
quoted above is wrong or misleading and that a frame switch should 
actually exit an incremental search.  In which case this bug would be a 
wontfix.

I'm fine with that point of view as long as I'm allowed to let frame 
switches keep isearch alive in some way or other.  I understand that the 
buffer switch (resulting from the frame switch) during an isearch is 
evil, but I frequently just alt-tab to a different frame, peek something 
there, alt-tab back, and continue the isearch.