In the left tree view, look for "Window Borders - PerPixel" .... expand that heading, and you'll find
Buttons
Borders - Bottom
Borders - Left
Borders - Right
Caption.... (this is the titlebar)
etc.
This is where you set the "Translucent" frames, and titlebar buttons. (Magic pink will not work for translucency)
Translucent menus are under the Controls heading.