I get this error when using e.g. hardcode-tray: Gtk-Message: (for origin information, set GTK_DEBUG): failed to retrieve property `gtk-primary-button-warps-slider' of type `gboolean' from rc file value "((GString*) 0x30e9320)" of type `gboolean' It's because kde-gtk-config puts this (apparently GTK+ 3 only) line in ~/.gtkrc-2.0: gtk-primary-button-warps-slider=false Steps to reproduce: Go to "System Settings > Application Style > GNOME Application Style" and save configuration.
*** This bug has been marked as a duplicate of bug 376273 ***