In Notes Client 9.0.x and 10.0.x, with default theme, you will find black bar behind "Open Mail" and "Open Calendar" icon present at top.
Requirement is to hide this black bar. It is not much presentable and doesnot emphasize if intention is to highlight these icons.
While changing theme, the black bar disappears but then these icons still get highlighted. However, the presentation after changing the theme looks good.