[Gtk] Fix link locations in labels
[Gtk] Fix link locations in labels

#251: GTK label backend finds links incorrectly

mminns/xwt,mono/xwt,TheBrainTech/xwt,sevoku/xwt,antmicro/xwt,lytico/xwt,hamekoz/xwt,cra0zy/xwt,steffenWi/xwt,akrisiun/xwt,residuum/xwt,directhex/xwt,mminns/xwt,hwthomas/xwt,iainx/xwt