ConcatWidget: Don't fail on extra kwargs
ConcatWidget: Don't fail on extra kwargs

pferreir/indico,DirkHoffmann/indico,mic4ael/indico,mvidalgarcia/indico,indico/indico,pferreir/indico,mic4ael/indico,OmeGak/indico,indico/indico,DirkHoffmann/indico,pferreir/indico,DirkHoffmann/indico,mic4ael/indico,mvidalgarcia/indico,ThiefMaster/indico,DirkHoffmann/indico,OmeGak/indico,OmeGak/indico,ThiefMaster/indico,mvidalgarcia/indico,OmeGak/indico,pferreir/indico,mic4ael/indico,mvidalgarcia/indico,indico/indico,ThiefMaster/indico,indico/indico,ThiefMaster/indico