[FIX] Make JLookupTabWidget.canvas work as intended
[FIX] Make JLookupTabWidget.canvas work as intended

- it's implemented in JTabWidget but only necessary/useful in
  JLookupTabWidget

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