Created attachment 168164 [details]
Trying to snap a window to the bottom right of a screen

SUMMARY
Any window using the default Breeze window decorations has an invisible 1px border / margin drawn around it.
This prevents windows from being snapped to the right or bottom sides of the screen and the background behind them stays visible.

The issue becomes especially noticeable if moving content (i.e. media) is played behind the window and "shines through" the 1px margin on the bottom and right sides.
This can also be seen in screenshots taken by Spectacle (if not including window shadow). Every screenshot will have a 1px padding on the bottom and right.

ADDITIONAL INFORMATION
- Does not affect fullscreen windows.
- No non-default scaling needed (100% scaling).
- Occurs on BOTH X11 and Wayland platforms.
- Oxygen and Plastik window decorations are NOT affected.
- Many third-party window decorations are NOT affected.
- Top and left edges of windows are NOT affected.

STEPS TO REPRODUCE
1. Use full KDE neon defaults / Use Breeze window decorations on a different OS
2a. Try to snap a window to the right side or the bottom of the screen
OR
2b. Try to snap a windows right or bottom edge to another window

OBSERVED RESULT
- The background behind the window will be visible around the window ("shines" through).
- The window does not properly snap to other windows or screen edges.

EXPECTED RESULT
The window should properly snap to other windows or screen edges, without any awkward margins.

SOFTWARE/OS VERSIONS
Linux: KDE neon Testing 20240402
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.1.0
Qt Version: 6.6.3

The issue occurs within the first 15 minutes on KDE neon. I just started the VM and tried to snap the Welcome Center to the side to reproduce it.