QtDesigner doesn't pull the slots from your source code, but from the ui file. So if you want to access them via designer, you'll need to right click an object and use the "change signals/slots" menu item. Add them there and they will appear.
BTW, the generated code by designer calls connectSlotsByName() which means that if you have a function like "void on_button1_clicked();" you don't need to connect() it, as it'll be done for you when you call setupui(). Saves doing it yourself.
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