add tooltip on undo rollback
add tooltip on undo rollback

abeyer/anki,hssm/anki,hssm/anki,jakesyl/ruby-card,weihautin/anki,Stvad/anki,weihautin/anki,LucasCabello/anki,xuewenfei/anki,eduOS/anki,Arthaey/anki,subfusc/anki,jakesyl/ruby-card,jkitching/anki,sunclx/anki,ospalh/libanki3,kenjhim/anki,florianjacob/anki,socialpercon/anki-1,holycrepe/anki,go38/anki