bug#70086: Mouse clicks in tab-bar don't call commands bound in keymap properties

[Juri Linkov]

> For example, given this value for global-mode-string:
>
> ((tab-bar-ecm-mode
>   (:propertize tab-bar-ecm-lighter keymap
>              (keymap
>               (tab-bar keymap
>                        (mouse-1 lambda
>                                 (&rest _)
>                                 (interactive)
>                                 (message "tab-bar-ecm-lighter clicked with 
> mouse-1"))))))
>  (listen-mode
>   (:propertize listen-mode-lighter keymap
>              (keymap
>               (tab-bar keymap
>                        (down-mouse-3 . listen-pause)
>                        (down-mouse-2 . listen-pause)
>                        (down-mouse-1 . listen-pause)
>                        (mouse-3 . listen-pause)
>                        (mouse-2 . listen-pause)
>                        (mouse-1 . listen-pause))
>               (mode-line keymap
>                          (mouse-1 . listen-pause))))))
>
> When I click on the text rendered by listen-mode-lighter, the lambda from
> the tab-bar-ecm-lighter keymap intercepts the mouse-1 event and prints the
> message rather than calling the listen-pause function.

Could you please distill this example into a self-contained test case
like you did the previous time, that helped a lot.