Hello,

Having a small issue with the kwin compositor and firefox. Whenever I run a new firefox process all transparent windows become 100% opaque with a black background. This is 100% reproducible. I can resolve this by toggling the setting: settings -> compositor -> allow applications to block compositing. However its getting cumbersome having to repeat this every time I need to open firefox. Any advice on how to debug/resolve this?

System specs:
gentoo
Linux 5.4.80-gentoo-r1 x86_64 Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz GenuineIntel GNU/Linux
plasmashell 5.19.5

lspci output:
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 08)
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #5 (rev f1)
00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point LPC Controller/eSPI Controller (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 10)
02:00.0 Network controller: Intel Corporation Dual Band Wireless-AC 3165 Plus Bluetooth (rev 99)

Hi!

I do not know exactly what causes your problem, but you can try to use another GTK-Program like gimp (GTK2.0) or gnome-calculator (GTK3.0) to check if it is caused bei GTK. Do you use the kde-gtk-config to provide a GTK-Theme? Perhaps this theme is faulty, causing KWin to switch off the composer stuff.
Does your system also provides useful log-information like systemd/journalctl, dmesg, syslog? That would be the first place to look at.

koffeinfriedhof wrote:Hi!

I do not know exactly what causes your problem, but you can try to use another GTK-Program like gimp (GTK2.0) or gnome-calculator (GTK3.0) to check if it is caused bei GTK. Do you use the kde-gtk-config to provide a GTK-Theme? Perhaps this theme is faulty, causing KWin to switch off the composer stuff.
Does your system also provides useful log-information like systemd/journalctl, dmesg, syslog? That would be the first place to look at.

I do use kde-gtk-config. I don't think I have a gtk-theme set however, is there a way to check for that? I tried gimp, gnome-calculator, even thunderbird but those all worked fine. Only firefox seems to cause this.

I checked anything relevant in /var/log like dmesg/syslog/messages and no logs related to kde show up.

Thank you for the help

Hi!

I don't think I have a gtk-theme set however, is there a way to check for that?

The integration itself takes place in some parts of the system, see the github information to get an overview. In `systemsettings5 kcm_style` there is a general setting for GTK2/3-Themes.

Perhaps you can get some more information using KWin-Debugging comparing before and after the start of firefox. Do you use X11 or Wayland? How is your open gl setup? Firefox has a setting called layers.acceleration.force-enabled which you can check to enable / disable.