Cut'n'paste question (WM)

G'day all. For reasons that may be summarized in a separate posting, I am accustomed to KDE, KMail, etc., but have recently found myself in Windowmaker, using Sylpheed Claws. I don't know if it's a Sylpheed thing, or a Windowmaker thing, but while URLs are highlighted within the Sylpheed message-view pane, they do not launch a browser. So, I select a URL as text, activate a browser manually, and paste. This works for Mozilla, but not for Opera. I'm fairly sure that I could paste URLs into Opera from other apps, in KDE. Am I misremembering, or is this a difference between WM and KDE? /kevin