There are two views in Font Book which show you a preview of the font. One is to the right of the font list, and the other appears in a separate window when you double-click a font. This second preview window needs some attention. For example, select the “Fixed Width” collection. Double-click “Apple Color Emoji”. The preview of the font will render as six question marks. If you select them and paste them elsewhere, you can see that the characters spell out the string “(null)”.

The same thing happens for “Apple Braille.” The bit of code that chooses which preview text to show for a font is returning “(null)” for these fonts, which is what the C library’s printf function returns when you give it a null pointer.

What happened here? Did nobody at Apple ever click this font and wonder why there was a row of question marks? Did nobody suggest that the preview text for Apple Color Emoji should include at least one emoji?

The preview area in the main Font Book window doesn’t have this issue, but it has its own issues. Its toolbar lets you choose four views of a font: preview text, glyph grid, custom preview text, and information. (The toolbar offers no option to display labels under these buttons. They do not have tooltips.)

In the “custom preview text” view, you can enter your own preview text to see it in the selected font, but the editor is all janky and glitchy. First of all, you have to click the text to turn it into a text box, then edit it, then tab away. But the text as you’re editing it in the text box looks the same as the rendered text anyway, just with an ugly black border. It would have been slicker to just let you edit the text live. The text box is also a couple of pixels smaller while you’re editing it, probably because of the black border, which causes the lines to break differently, so the text reflows distractingly when you tab in and out too.

Worse, when you tab away after editing the text, the previous text flashes on the screen for a split-second before being replaced by the new text you just entered.

The editor is even more glitchy when using IMEs to type in non-Latin scripts. After you select and delete the default preview text in such a font (which will render as all question marks, since the default text for all scripts is Lorem Ipsum), the IME will not function until you tab away from the text box and back again.