After switching desktop background to "Workspace" mode, icons and plasmoids near the bottom move up, when the control bar is drawn (and no splash screen is enabled). STEPS TO REPRODUCE 1. Switch to Workspace mode 2. Add icons to the bottom (but above control bar) 3. Relogin OBSERVED RESULT The icons/plasmoids move up, and the location persists. EXPECTED RESULT Icons/plasmoids keep their location. SOFTWARE/OS VERSIONS Linux/KDE Plasma: openSUSE Tumbleweed 20200721 KDE Plasma Version: 5.19.3 KDE Frameworks Version: 5.72.0 Qt Version: 5.15.0 ADDITIONAL INFORMATION The problem is not reproducible. I'm maintaining about a dozen similar setups, were one suffers from this issue. That one has two 30" screens with 2560x1600. Here's a mp4 recording of the issue: https://drive.google.com/file/d/15p7E79owOOQn_u2-wi6u8PusxjAVssm9/view?usp=sharing
Thanks Nate for refining the Summary. A small description of the video is also missing: It starts with showing the lower left corner of sddm (with a custom background: vladstudio_kihot_1600x1200). @00:00:06, the desktop icons are drawn, @00:00:24, the background image is drawn (vladstudio..) @00:00:30 the panel appears, and the icons move up one second later. You can see that relative to the sun flowers. Icons, that are located near the top of the screens keep their locations, btw. It would be much easier to deal with this situation, if it would be possible to move all icons at once (rubberband..), but since all items in this mode are plasmoids, that isn't available. Just one more note: I was using the desktop folder view since its dawn in KDE 2 or 3 (?!?) times. Unfortunately, during the last few month, that became increasingly unstable, such as "forgetting" the icon locations. (running many revisions of openSUSE Tumbleweed). Yes, I know, that a lot of advancements happened in KDE land in that time, and I welcome that. Will try to examine changes in plasma-org.kde.plasma.desktop-appletsrc, as suggested from Fabian Vogt. Funnily, due to the folder view issues, I still have a script active, that creates backups (hardlinks) of the appletsrc file before session start and during logoff. If somebody wants to examine them, I'm happy to share them (but would like to avoid to make them public).
Comparing the appletrc files of the affected system with a sane one reveals, that those moving items appear in the itemsOnDisabledScreens list of the ScreenMapping section, were the list on the unaffected system is empty.
While itemsOnDisabledScreens seems to be a red herring, I wrote a small script, that workarounds this issue temporarily by fixing the vertical position of dislocated items with a crude heuristic, based on appletsrc backups. https://invent.kde.org/snippets/1074
Updated version 5.23.4 I found a better workaround for this behavior. The problem only appears after logging in. Thus, if I kill plasmashell after startup (Ctrl-Alt-Esc -> click on background), and restart manually (Alt-F2 -> plasmashell), the icons keep at the desired positions. So it boils down to some delay/race, when the panel is drawn for the first time, it moves the lowest items (icons, plasmoids) up ~64 pixel, even if the items wouldn't be obscured from the panel.
The panel setting is static (not auto-hidden).
*** This bug has been marked as a duplicate of bug 458007 ***