right click on your wallpaper, select "configure desktop" change "layout" setting, click 'ok" button desktop settings window is unnecessarily reopened If the user wants to keep desktop settings window opened after to change "layout" setting, "apply now" and "apply" buttons can be used.
I can confirm this issue.
*** Bug 419866 has been marked as a duplicate of this bug. ***
Oh, search function on bugzilla is so hard to use = = ... Anyway, if anyone more familiar with QML wants to have a look see the debugging I did at https://bugs.kde.org/show_bug.cgi?id=419866.
Confirmed.