Bug 512857

+++ This bug was initially created as a clone of Bug #469727 +++

SUMMARY
Unable to set border size via global theme. Added keys specified to the "defaults" file, but it does not appear to be applied. The option for Window Size does show up when applying the global theme and does not appear to show up on themes that do not have the setting, but when applied, no changes are visible.

STEPS TO REPRODUCE (directions in merge request)
1. Create a global theme
2. Add the keys for BorderSize specified in the merge request to the global theme
3. Apply the global theme, ensuring that the "Window Size" option visible in "Choose what to apply..." is checked.

OBSERVED RESULT
Window decoration does not appear to change border size and borders reflect their usual size.

EXPECTED RESULT
Window decoration should change to the border size specified in the global theme.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: CachyOS Linux
KDE Plasma Version: 6.5.3
KDE Frameworks Version: 6.20.0
Qt Version: 6.10.0

ADDITIONAL INFORMATION
SUMMARY
It is a bit confusing as to what goes where since different settings work in different, but similar-looking files. E.g. The "defaults" file in the Global Theme's "contents" and the "defaults" inside its "layouts" folder.

STEPS TO REPRODUCE
1. Create a Global theme (a dummy theme named "w" is attached, it is extracted to ~/.local/share/plasma/look-and-feel/)
2. Inside the theme's "contents">"layouts" folder, create a file named "defaults"
3. Add the following to the file:

[kwinrc][org.kde.kdecoration2]
ButtonsOnRight=SFM
BorderSize=Tiny

4. Save the file and apply the Global Theme with its layout

OBSERVED RESULT
The buttons are changed, but the border size remains Normal.

EXPECTED RESULT
The buttons should change and the border size should be set (to Tiny in this case).

SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.27
KDE Plasma Version: 5.27.4
KDE Frameworks Version: 5.105.0
Qt Version: 5.15.8
Kernel Version: 5.19.0-38-generic (64-bit)
Graphics Platform: X11

ADDITIONAL INFORMATION
This bug may be in the wrong place.