Interesting…well I mostly went through the very very extensive Spectacle bugs and decided my eyes are too tired for this.
If you’re using kde-unstable you’re probably aware that you also have to enable core-testing and extra-testing.
But maybe you’re just one of the kde-unstable only connoisseurs. Qt 6.9.1 is in extra testing, which also resulted in a new kwin-beta build in kde-unstable.
Don’t update kde-unstable/kwin without having received Qt 6.9.1…
Just as a heads up. I didn’t try, but I assume it will break.
I tried. Didn’t break for me.
Plasma 6.4 is out 
Unless I missed it by mere minutes, Arch hasn’t let the floodgates open yet though :0
Some great stuff in the announcement
I have NONE! Gimme now! (lol)
Hurry, hurry, hurry - it’s in repos! 
EDIT: success and new Firefox too
(140) Which somehow manages to break GTK window control buttons. 
It was perfectly integrated (breeze) until about an hour ago or so.
Downgrade return previous breeze styled buttons, but is not really an option.
Does it? I didn’t notice… I use two finger swipe to navigate back and forth between pages and occasionally I need to close and reopen Firefox if that functionality isn’t working, but seems OK here. Do you have an example?
Sorry I was posting the scrot above.
But you can see there .. I have kate and gimp open to show GTK and QT matching .. but firefox is the lone standout having its own controls (the pink highlight is my own annotation).
I have had my own css in userChrome.css for various things and that included some styling for those controls but I’ve also checked removing it and a few related about:config options .. nothing seems to make it budge .. but 139 looked/looks as it should. As does firefox --ProfileManager.
Maybe something to just wait out.
Updated 
.
I saw another linux-firmware updates.
Yes, that is one of the newer ones I tried to toggle.
In the past it did not exist and I relied on my own CSS.
Still no combination resulted in anything other than what must be the default embedded ff controls.
While yours seems to be properly presenting breeze controls.
I have tried a fresh profile as well.
This is a difference. I suppose I will try that.
Result: Did not seem to make a difference adding the extension and restarting.
Maybe it would be interesting to know if it followed any GTK theme setting.
Though what I am trying for here is breeze.
Just a double check - what firefox theme? Just the “System Theme / Auto” ?
Maybe I might ask about a few packages that are sometimes mentioned.. do you happen to have gnome-settings-daemon or gsettings-qt installed (I do not)?
System Theme - Auto is Enabled and Breeze system theming here
pacman -Qs gnome-settings —> No Results
pacman -Qs gsettings results in:
local/gsettings-desktop-schemas 48.0-1
GSettings schemas for GNOME desktop components
local/gsettings-system-schemas 48.0-1
GSettings schemas for GNOME system components