Works like a charm.
(Titles are restored after closing a window or even killing firefox completely. I didn’t try a reboot yet.)

man klickt auf das Icon, Ein Popup Fenster erscheint, man tippt einen Namen ein, und ab dann heißst das Fenster "[eingegebener Name] Tabname"
also alles wie man es erwarten würde, einfach und funktioniert.

Works great on Mac, and Linux.

For those having issues accessing the shortcut because it conflicts with one previously set by your OS, or another extension, you can manage the shortcuts yourself - just go to your extensions page, click on the cogwheel (tools for all add-ons), and then select the "Manage Extensions Shortcut"

For those who don't see the toolbar icon, remember it may be hidden in the extensions icon (puzzle piece), if you haven't already opted to pin Window Titler to the toolbar.

Awesome little helper. I use it together with a mod that lets me shorten task bar tabs. Makes my life as a tab hoarder so much more tidy. :D

Using for KDE Window Rules. I need to differentiate between various FF windows to handle them differently. Setting the window title makes it possible as otherwise all FF windows have the same window class/role/type/everything.

The only drawback is that the title is not set immediately when the window is created, but only several milliseconds later. Causing flickering.

Thank you!

Works well for me so far. Even remembers titles between sessions. Update: titles do disappear once every 2-7 days or so, from all windows at once, but they're remembered when opening the plugin, so you just gotta open it and press enter for each previously named window, when that happens.

Also, i love that these features are included:
Customizable keyboard shortcut, customizable brackets around the title and option for auto title prefix.

Works well. It'd be nice if the custom titles showed up in the History > Recently Closed Windows menu, but perhaps that's a limitation of Firefox?

Essential for auto-placement with a sane window manager (like sway …).

Does its job perfectly!

「＜ウィンドウ名＞タブのタイトル」という形式で表示する事ができ、「ツリー型タブ」と合わせて便利に使っています。

作業目的ごとにウィンドウを作る使い方をする中で、開いているタブによってはウィンドウの役割が分かりにくい悩みがありましたが、解消されました。

Does exactly what it says. Love that it persists through session restore. Perfect little addon