When you select a Term (say, an ingredient or a Course) from a Dictionary pop-up menu, the selected Term will appear in the box. Otherwise, the boxed pop-up menu will show the Term. For more on providing Terms using a Dictionary pop-up menu and a text box together, see Specifying a Term under How To.
Anytime a Dictionary pop-up menu appears aside a text box, you can type the Term into the box; if you want to provide more than one Term, just separate them with commas. In these cases, holding down the Shift key when selecting from the pop-up menu will add the Term you select to the text box without affecting the Terms already there.