If any window title of Safari contains x then

It's not that Safari can't see them. It's that the Safari window title changes to what tab is selected. KM only sees the actual window title, therefore it only sees the active tab's title.

For example:

Using the aforementioned Window Discovery Tool, this is what windows are available for Safari:

------------------------------
Safari
------------------------------
window →  Google 

So, the active tab is "Google", and that's what Safari's window title is.

Now if I switch to the Amazon tab:

...we get this:


-------------------------------------------------------------------------------------------
Safari
-------------------------------------------------------------------------------------------
window →  1 
window →  Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs & more 

(I have no idea what window "1" is.)


So when KM looks for window titles, it looks at the actual window title, not the tab title. It just so happens that Safari changes its window title to match the active tab's title.

Hope that makes sense.