Version: (using Devel) OS: Linux Revision: 820071. The notes and the notify plasmoid, maybe some others as well, show a white background instead of a yellow one, in case of the notes plasmoid. This is using the default plasma theme.
When you change the Style in SystemSettings from Oxygen to something else, the background is OK again so I guess it should be re-assigned to Oxygen devels!
Reassigning, Marco thinks it's oxygen.cpp line 2021 widget->setAttribute(Qt::WA_StyledBackground);
yeah, can confirm, removing that line the problem goes away, since we use a lot Qt::WA_NoSystemBackground it seems that overrides it.
SVN commit 820123 by boemann: Try fixing a bug with oxygen background and plasma CCBUG:163945 M +3 -3 oxygen.cpp WebSVN link: http://websvn.kde.org/?view=rev&revision=820123
Reported as working by Marco
*** Bug 164661 has been marked as a duplicate of this bug. ***