bug#50779: 28.0.50; Tab bar doesn't respond to mouse clicks

[Po Lu]

Daniel Semyonov <daniel@dsemy.com> writes:

> Note: tested only in a Wayland session (sway) with pgtk.
>
> The tab bar doesn't respond to any mouse clicks (switching tabs by clicking
> them doesn't work, creating a new tab by clicking the "+" doesn't work,
> etc.).
> However, the tab line (tab-line-mode) does seem to work (although I only
> did minimal testing since I don't use it normally).
>
> Recipe:
> 1. emacs -Q
> 2. M-x tab-bar-mode
> 3. Click on any tab or button in the tab bar.
>
> Thanks!
>
> Daniel

I tried to fix this.  Please pull latest feature/pgtk and test, thanks.