When the top/bottom panel is not maximized horizontally the theme puts a black stripe to each side. This also happens for vertical panels. Other themes are not affected. I also removed all plasma-related kcache-files in /var/tmp/kdecache-ME with no success. Reproducible: Always
Created attachment 76953 [details] screenshot
As I get this now with several other themes I looked further into it: Some themes seem to to have sort of a minimum size. When scaling the panel smaller that that size shadows seem to overlap and produce that ugly thin black line. Themes that don't suffer from this are e.g. Oxygen, Air for netbooks and Slim Glow. Air and Appows suffer from this issue. As some themes have shadows but indeed work without issues this may be a problem in the rendering code. -> kwin? plasma?
The root of this issue: e.g. take the stripe on the left of a top-panel. It appears if "actual_shadow_height < heightof#shadow_topleft + heightof#shadow_bottomleft". In that case shadows overlap. If I take "Air for netbooks" and reduce the height, I also will get the stripe. As a solution I could imagine to simply add an offset to the shadow instead of insisting on the absolute position of #shadow_topleft.
Hello! This bug report was filed for KDE Plasma 4, which reached end-of-support status in August 2015. KDE Plasma 5's desktop shell has been almost completely rewritten for better performance and usability, so it is likely that this bug is already resolved in Plasma 5. Accordingly, we hope you understand why we must close this bug report. If the issue described here is still present in KDE Plasma 5.12 or later, please feel free to open a new ticket in the "plasmashell" product after reading https://community.kde.org/Get_Involved/Bug_Reporting If you would like to get involved in KDE's bug triaging effort so that future mass bug closes like this are less likely, please read https://community.kde.org/Get_Involved#Bug_Triaging Thanks for your understanding! Nate Graham