Hi, Where do you get that ID ? You'll click on the action, get the ID and then call the slot ?

@SGaist said: Why will it not work ? AFAIK that's the goal of QSignalMapper: to map several objects to one signal with a parameter of known value. I seem to have missed my morning coffee when I wrote that. Sure it will work.

Hi and welcome to devnet, MainWindow's theme is a signal so basically your initial connect line was correct from that perspective. However, your theme function is just a static function somewhere. If you want it to be called, you should make theme a slot, and add the missing MainWindow:: between void and theme and keep the new version of the connect statement.