the default brower of xchat 2.8
The logic to find default brower is changed from xchat 2.6.8 to 2.8.
The 2.8 xchat will call xdg-open to open brower, in KDE, xdg-open will call konqueror unless you have set KDE's default brower to others.
I like firefox, and older version of xchat used to call firefox for me.
So I set KDE's default brower in kcontrol: KDE components-> Component chooser -> Web brower.