Created attachment 144850 [details] The wallpaper is visible between the panel and the open calendar SUMMARY The 1px separator line that separates plasmoids from the panel does not look good with other themes. Other themes show an awkward gap between the panel and the plasmoid. STEPS TO REPRODUCE 1. Choose a theme other than Breeze (e.g. Oxygen) 2. Open a plasmoid (e.g. Kickoff) 3. OBSERVED RESULT There is a 1px gap between the plasmoid and the panel EXPECTED RESULT It seems to be better hidden on Breeze. I expect a line to be drawn (ideally if the theme designer wanted it) with the panel and plasmoid connected continuously. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION I think dialog.svg with line.svg on top would better support themes. Moving the separator line to the header and footer may be a better choice, though much more complicated.
Are you on X11 using a hidpi scale factor? If so, this could be Bug 391956. Cannot reproduce on Wayland with 200% scale.
(In reply to Nate Graham from comment #1) > Are you on X11 using a hidpi scale factor? If so, this could be Bug 391956. > > Cannot reproduce on Wayland with 200% scale. Nope, X11 at 100%. Tested on Arch X11 and X11/Wayland in a Neon VM. It seems it is only visible when the panel is set to "translucent," but I haven't checked 200% scaling.
Worryingly, it seems that themes have taken to making the horizontal element in line.svg opaque to cope with the separator line being used between the panel and plasmoids. Since Breeze assumes that the separator line is always text color, a designer preserving a black outline style (e.g. Mega) and hard-coding the line to be black will also make the separator in notifications black. Thus, the line separating the panel from Kickoff will be black, but the separator between notifications will now also be black. I've realized now that it's visible in plain Breeze as well, though the horizontal lines are hidden better because of opaque footers and generally higher opacity. The vertical lines that show when a plasmoid is against the left or right of the screen reveal the gap if one looks below the header/footer. Willow Dark, having very low opacity in line.svg, shows this most clearly. If a plasmoid is in front of a flat and dark background, the text color line.svg element shows the way it was intended for Breeze.
Created attachment 146622 [details] Separator between plasmoids
The horizontal separator line comes from line.svg and is used in separating notifications as well. The clipboard uses the separator from listitem.svg. In my case, menus should have a black frame, thus my line.svg is close to background color. The separators for text content should be text color. The notification separator should use something other than the separator for panels and plasmoids (e.g. listitem's separator). However, I cannot know where the vertical separator line comes from without reading the code. The horizontal line updates with line.svg, but the vertical appears not to.
Final status of this bug: Line.svg is used to separate plasmoids from the panel. Line.svg is also used in the Audio Volume plasmoid to separate Devices. The clipboard may be using listitem.svg's separator. The 2 are functionally different. One to separate plasmoids from panel, one to separate items in a list. In the case of themes with dark lines to separate plasmoids from the panel, such as in Willow Dark, this means that the separator in Audio Volume will be almost invisible. Audio Volume and other separators should use listitem.svg's line and not the one used to separate the panel from plasmoids.
Created attachment 148044 [details] top to bottom: Kickoff, Audio Volume, Clipboard
Seems reasonable. We can fix that.
From what I can tell, this hasn't been fixed. Interestingly, it seems that the separator for the clipboard has been completely removed altogether. Previously, that was achieved by making it invisible in the svgs so it could optionally be included. Audio still seems to be using the same line.svg that separates the panel and under Willow Dark, the separator is black instead of text color. I think the complexity of theming decisions has crossed too far into philosophy. Do you suppose there needs to be some discussion for Plasma 6 to decide on things/defensive design practices so it isn't war with themers at every update?