With the latest version of webkit-gtk (1.6.1-r200 in my Gentoo repository) the plugin does not load because of the missing symbol 'webkit_web_view_get_selected_text'. Also the plugin cannot be built against GTK 3.x because GtkAdjustment is an opaque object now and so the 'value' property is not longer directly accessible. The attached patch fixes all these issues. Please see this Gentoo bug for more information.
Created attachment 1036 [details]
fancy fix for webkit 1.6.x
Mm. The patch was not picked up by the initial edit.
Adding the GtkAdjustment bit in CVS, thanks
*** This bug has been marked as a duplicate of bug 2507 ***