After selecting KMail as the "mailto" client in Firefox (Preferences => Applications) the KMail composer is invoked on a "Send Link..." action but the link name and address are not automatically loaded into the "Subject" and "message body" fields respectively. This might be a "wish" rather than a "bug" however I have gotten spoiled and lazy by the actions performed in KDE Konqueror/KMail. Using KDE 3.5.9 / Firefox 3.0.3 / KMail 1.9.9 on openSuse 11.0 Final (fully updated).