SUMMARY STEPS TO REPRODUCE 1. Set the window decoration to Breeze Dark 2. Set the window decorations border to normal 3. Open Dolphin OBSERVED RESULT The headerbar area is not separated with the line and blends with the rest of the app EXPECTED RESULT The headerbar area is separated and differs in color SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.22.2 KDE Frameworks Version: 5.83.0 Qt Version: 5.15.2 Kernel Version: 5.10.46-1-lts (64-bit) Graphics Platform: X11 Processors: 8 × Intel® Core™ i7-8550U CPU @ 1.80GHz Memory: 15,5 GiB of RAM Graphics Processor: Mesa Intel® UHD Graphics 620 ADDITIONAL INFORMATION It seems like this is intended behavior, because we assume that the underline, that stops at the border, that has the same color, as the upper and surroundings of the underline is odd. But this is not the case when we change the color border to something prominent (e.g. like in this screenshot: https://github.com/esjeon/krohnkite/blob/master/img/screenshot.png). Maybe the header area could be a configurable option in the Breeze style?
This is intentional. The header area was only designed to look good when SSD window borders are disabled, so we go back to the old look when SSD window borders are enabled.