https://bugs.kde.org/show_bug.cgi?id=393750

Firefox is interfering with KWin after an update in openSUSE Tumbleweed roughly a few hours ago. All other applications (including Thunderbird) work fine, but when I startup Firefox its window has no borders whereas the titlebar appears gray. The window can also not be resized, it can only be minimized / restored by dragging it from and to the screen edges.

I'm attaching a screenshot of the broken FF window. The gray titlebar is NOT the theme I'm currently using (Aurorae), and I have no idea what skin the buttons to its upper-right are from either. KWin should not be allowing applications to have custom window managers, this might be an issue with some fundamental library.

Interesting, could you post what you installed?

Should be in /var/log/zypper.log

Just great. Apparently this isn't a bug but some sort of new feature: It's called Client Side Decorations (CSD) and it basically means that Firefox now embeds and may use its own window manager, because why not break the OS with unnecessary functionality?

First off I created a KWin window rule to force the normal titlebar to show up again. This causes two titlebars to appear, as visible in the screenshot I'm attaching here.



I next had a chat on the Firefox IRC channel about this. Folks kept saying that it should be possible to disable with browser.tabs.drawInTitlebar in about:config, but that setting doesn't work for me and isn't intended until Firefox 60 from what I hear. The only thing that makes it go away is running FF with the following environment variable set:

Code: Select all

export MOZ_GTK_TITLEBAR_DECORATION=none