When clicking on some maximized or tiled windows, focus on roughly the lower quarter falls to the window behind

[Jacob Godserv]

Initially I thought this was an issue with IntelliJ and filed a bug there:
https://youtrack.jetbrains.com/issue/IDEA-323780/Maximizing-the-the-window-sometimes-causes-clicks-on-a-lower-fraction-to-pass-through-to-the-window-behind

But when I had the same issue with GIMP, I realized it's an Ubuntu or GNOME issue instead. I am assuming this is a gnome-shell problem.

Every once in a while, when I maximize or tile (Win+Right) the IntelliJ window, a bottom fraction of the window (somewhere around a quarter) becomes impossible to interact with, with the mouse. Clicking in that lower area will give focus to the thing behind IntelliJ, and if it's a window, raise it to the foreground. if I restore the window so that it is not maximized, the entire window is interactive with the mouse once again.

This also happened with GIMP.

The attached "Screencast" is a recording. I had to crop it to hide personal information. The attached screenshot shows the state of my screen so you have context, with a bright green color used to replace personal information.

For the first 10s of the recording, I simply moused over to show how the cursor changes around a quarter from the bottom of the screen.

For the next 10s, I left click, then move, then left click, then move, until focus changes to Sublime, the window behind IntelliJ.

For the remainder of the video I show that right-clicking and mousing over works fine on the top three quarters, until I reach the bottom again, and then the right click is sent to Sublime.

Ubuntu 23.04
gnome-shell version 44.2-0ubuntu1

ProblemType: Bug
DistroRelease: Ubuntu 23.04
Package: gnome-shell 44.2-0ubuntu1
ProcVersionSignature: Ubuntu 6.2.0-24.24-generic 6.2.12
Uname: Linux 6.2.0-24-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.26.1-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Jul 5 12:05:46 2023
DisplayManager: gdm3
InstallationDate: Installed on 2022-09-19 (289 days ago)
InstallationMedia: Ubuntu 22.04.1 LTS "Jammy Jellyfish" - Release amd64 (20220809.1)
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/usr/bin/zsh
 TERM=screen-256color
 XDG_RUNTIME_DIR=<set>
RelatedPackageVersions: mutter-common 44.2-0ubuntu1
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

[Jacob Godserv (fun2program8)]

As mentioned in OP, here is the screenshot showing context of entire desktop, with bright green hiding personal information.

[Daniel van Vugt (vanvugt)]

This is probably a bug in mutter but before we can report it upstream it would be best to try and reproduce the bug without having the unsupported extension '<email address hidden>' installed. So please remove that extension and check the bug still occurs.

[Jacob Godserv (fun2program8)]

I thought I had removed all unsupported extensions.

Here is my extension setup:

# gsettings get org.gnome.shell enabled-extensions
['<email address hidden>', '<email address hidden>']
# ls -l ~/.local/share/gnome-shell/extensions
total 0
#

The issue still occurred.

[Jacob Godserv (fun2program8)]

Sorry, I should have added that I had seen those extensions as well once the bug report was up, and removed them and re-logged. The issue occurred again today.

[Jacob Godserv (fun2program8)]

Current workaround appears to be:
1. "Un"-maximize the window (aka "restore" the window)
2. Interact with the window at least once.
3. Maximize the window again.

This appears to somehow work around this focus "click through" issue.

[Jacob Godserv (fun2program8)]

Interestingly, this also happened once where the right quarter was clicking through as well. I noticed this when trying to interact with the title bar buttons (minimize, restore, close) and I ended up clicking the title bar buttons of the window behind.

[Jacob Godserv (fun2program8)]

One thing I've found is this is a high frequency occurrence with IntelliJ. I have not seen this issue with the snap versions of Sublime Text or Firefox. I did experience the issue in the snap version of GIMP the one time I had it open.

Another interesting effect is that I am unable to resize the window in the lower corners, even if all the elements within the window are otherwise behaving normally. This is not true of Firefox or Sublime.

In addition, Sublime and Firefox render shadows outside their window borders, whereas the IntelliJ window does not.

I have no idea if any of this is related.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Tais P. Hansen (taisph)]

I think this might be similar to what I've experienced lately. It seems like it is definitely triggered after a window resize, both manual and automatic. After the resize, button clicks seems to fall through the window to whatever is behind it. Reproduction is reliable so I can even record a video of it happening if it helps.

This is on Ubuntu 23.10, mutter=45.2-0ubuntu3, Xorg.