Bug 471131

SUMMARY
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***


STEPS TO REPRODUCE
1. Allign 2 Screens horizontally with the kscreen gui
2. Align to the border between the 2 screens or maximize a window.

OBSERVED RESULT
The window protrudes one screen and its outer vertical 1 pixel wide bar is shown on the other screen

EXPECTED RESULT
The window is only shown on one screen.

                   -`                    
                  .o+`                   ------------ 
                 `ooo/                   OS: Arch Linux x86_64 
                `+oooo:                  Host: MS-7D54 1.0 
               `+oooooo:                 Kernel: 6.3.8-arch1-1 
               -+oooooo+:                Uptime: 21 mins 
             `/:-:++oooo+:               Packages: 2112 (pacman), 7 (flatpak) 
            `/++++/+++++++:              Shell: zsh 5.9 
           `/++++++++++++++:             Resolution: 3840x2160, 3840x2160 
          `/+++ooooooooooooo/`           DE: Plasma 5.27.5 
         ./ooosssso++osssssso+`          WM: KWin 
        .oossssso-````/ossssss+`         WM Theme: Breeze 
       -osssssso.      :ssssssso.        Theme: Breeze Dark [Plasma], Adwaita-dark [GTK2/3] 
      :osssssss/        osssso+++.       Icons: breeze-dark [Plasma], breeze-dark [GTK2/3] 
     /ossssssss/        +ssssooo/-       Terminal: konsole 
   `/ossssso+/:-        -:/+osssso+-     Terminal Font: Hack Nerd Font Mono 10 
  `+sso+:-`                 `.-/+oso:    CPU: AMD Ryzen 9 3900X (24) @ 3.800GHz 
 `++:.                           `-/+/   GPU: NVIDIA GeForce RTX 3070 
 .`                                 `/   Memory: 6407MiB / 15914MiB 

Operating System: Arch Linux 
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.107.0
Qt Version: 5.15.10
Kernel Version: 6.3.8-arch1-1 (64-bit)
Graphics Platform: X11
Processors: 24 × AMD Ryzen 9 3900X 12-Core Processor
Memory: 15.5 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 3070/PCIe/SSE2
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7D54
System Version: 1.0

ADDITIONAL INFORMATION

Output of xrandr with bug:
$ xrandr
Screen 0: minimum 8 x 8, current 7680 x 2160, maximum 32767 x 32767
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected 3840x2160+3840+0 (normal left inverted right x axis y axis) 621mm x 341mm
   3840x2160     60.00*+  59.94    50.00    30.00    29.97    25.00    23.98  
   1920x1080     60.00    59.94    50.00  
   1680x1050     59.95  
   1440x900      59.89  
   1280x1024     60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       59.94    59.93  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 621mm x 341mm
   3840x2160     60.00*+  59.94    50.00    30.00    29.97    25.00    23.98  
   1920x1080     60.00    59.94    50.00  
   1680x1050     59.95  
   1440x900      59.89  
   1280x1024     60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       59.94    59.93  
DP-3 disconnected (normal left inverted right x axis y axis)

Fixed with xrandr:
$ xrandr --output DP-0 --pos 3841x0
$ xrandr
Screen 0: minimum 8 x 8, current 7681 x 2160, maximum 32767 x 32767
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected 3840x2160+3841+0 (normal left inverted right x axis y axis) 621mm x 341mm
   3840x2160     60.00*+  59.94    50.00    30.00    29.97    25.00    23.98  
   1920x1080     60.00    59.94    50.00  
   1680x1050     59.95  
   1440x900      59.89  
   1280x1024     60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       59.94    59.93  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 621mm x 341mm
   3840x2160     60.00*+  59.94    50.00    30.00    29.97    25.00    23.98  
   1920x1080     60.00    59.94    50.00  
   1680x1050     59.95  
   1440x900      59.89  
   1280x1024     60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       59.94    59.93  
DP-3 disconnected (normal left inverted right x axis y axis)