Playlist pane is a technical term referring to a UI element, therefore it should be in italics as a whole. You could have the Playlist pane if Amarok displayed Playlist as a label — but it does not.
Your information is wrong, sorry. Playlist IS the label when Amarok is tabbed. "Pane" should never be capitalized or marked up.
In contrast, the various labeled parts of Amarok should be capitalized if Amarok does, and not where Amarok does not, but always be marked up in italics.
I've spent time correcting this error and others, and I would definitely prefer not to have to come along behind you and correct it again! Consult Amarok and the experts in #amarok and #rokymotion before changing Userbase pages. This is a team effort; if you are part of our team, please help us, and help us help you. Also, you might want to join the Amarok-promo list, where we discuss these issues. We're almost done with the Handbook, and would really like to polish and finish it.
Study the userbase markup pages and help us get everything perfect, so we can get this translated and put into Docbook.