Rectangular chronograph buttons

[Passionata]

please educate me , i understand how screw in type buttons are fitted , , basically a tube screwed into the case which holds the stem with the pusher , but how the rectangular ones are fitted -the ones where the button slides INTO the case , here s a pic from patek obviously w/o the answer to my question



is there a "hole" in the case which holds the tube and let the pusher sliding in ?

thanks