After playing a little bit, I realized that my toolbar did in fact work as “expected” (read: expected by an experienced OS X toolbar customizer).
The problem I thought I had run into was that I couldn’t drag the new elements on the toolbar. Actually, I was trying to drag them onto the default toolbar (which appears in the sheet that is activated by the “Customize Toolbar” menu item).
What I actually had to do was drag the new items onto the actual toolbar of the application. My bad. Once I realized the error of my ways, all was well. So following the steps in the previous post should be enough to create a visually complete toolbar whose customization works as expected.
