I wanted to edit the default ksplashqml theme to include a background image. Adding the image was easy enough to the existing Splash.qml in /usr/share/plasma/look-and-feel/org.kde.breeze.desktop/contents/splash but of course whenever there's is an update it gets overwritten to the default again. So I tried copying just the splash folder contents to vishal@skybird:~/.local/share/plasma/look-and-feel/org.kde.vishal.desktop/contents/splash and also modified the metadata.desktop file (to name it org.kde.vishal.desktop to avoid clashing with breeze) and while that seems to work for the splash screen theme, but it also creates a new item under "look and feel" settings. I guess this bug report might be a wishlist to move the theme config load/save away from the overall "look and feel" package/KCM config group so that it's easy for people to create new QML splash themes and configure it in the Splash Screen KCM separate from the selected (default Breeze) Look and Feel options. Looking around the code I couldn't figure out where the "splashmainscript" string literal is being used (loaded/saved) but I guess the code in ksplash QML and KCM portions would need to be updated: https://github.com/KDE/plasma-workspace/blob/master/ksplash/ksplashqml/splashwindow.cpp#L117 https://github.com/KDE/plasma-desktop/blob/master/kcms/ksplash/kcm.cpp#L108 Searching the code for "splashmainscript" found these other places: https://github.com/KDE/plasma-desktop/blob/master/kcms/lookandfeel/kcm.cpp#L194 https://github.com/KDE/plasma-framework/blob/master/src/plasmaquick/private/packages.cpp#L71 https://github.com/KDE/plasma-workspace/blob/master/shell/packageplugins/lookandfeel/lookandfeel.cpp#L71 Although I'm reporting this for 5.7.95 I guess this is too late for the LTS and I hope this might be addressed for 5.9 Reproducible: Always
Added bug # 358839 to the "see also" field, that looks like a more effort wishlist. This bug is intended to ask for getting things started for ability to add/customise splash qmls.
The fact that you need to create a whole custom splash screen to persist your edits is currently intentional, and this is the way it works for any themable UI elements. That said, I agree that it's not ideal and seems fairly heavyweight for the simple case of just wanting to change the background; see Bug 355250. I've proposed some changes to the infrastructure here that would support this; see https://invent.kde.org/plasma/plasma-desktop/-/issues/93. Let's follow up there.