Finding letters fast in the Font by Zaweba glyphs grid
The glyphs grid in Font by Zaweba shows every character, styled or base, and filters by capitals, lowercase, figures, punctuation or the letters you edited.

A font has more characters than most people expect. Font by Zaweba starts every font from a base alphabet of 109, covering the printable ASCII set plus symbols such as the pound, euro and degree signs, curly quotes and dashes. Keeping an eye on all of them at once is the job of the glyphs grid.
The grid is exactly what it sounds like: a grid of every character in the font, laid out so you can scan the whole set. It's where you check that a change in the style stack has done what you meant to every letter, spot the one that looks wrong, and open it for editing.
Styled or base
The grid can show either the styled glyphs or the base glyphs. Styled is what your font looks like now, with weight, serifs, slant and every other operation in the stack applied. Base is the plain starting alphabet before any styling.
Switching between them is useful in two situations. When a styled letter looks odd, a look at its base version tells you whether the problem is in the letter itself or in how an operation treats it. And when you've edited letters by hand, the base view shows the underlying skeleton that the stack builds on.
Filters
Six filters narrow the grid down: All, Capitals, Lowercase, Figures, Punctuation and symbols, and Edited. The first five are about the kind of character. They're handy when you're working on one part of the font. If you've just added serifs and want to check capitals only, filter to Capitals and the grid shows just those, large enough to compare.
The Edited filter is the one people come to rely on. It shows only the glyphs you've changed. After a session in the glyph editor, or after importing an SVG glyph sheet that you've edited in another program, this is how you find every letter that differs from the base. It's also a good check before exporting a family: look at each edited glyph in the styled view and make sure it still sits well with its neighbours after the latest style changes.
Where the grid fits in your work
A typical session moves between three places. The style stack changes the whole alphabet. The live preview shows how real words look. The grid sits between them, showing every character on its own so nothing gets missed. A preview sentence might never include a question mark, a figure 7 or a curly quote, and the grid will show all of them.
From the grid you open a glyph in the glyph editor. There you can edit it in Skeleton mode, working on the centre line so weight changes stay clean, or in Outline mode, working on the outer shape. If the edit doesn't work out, Revert to base sets the glyph back to its starting form, and it drops out of the Edited filter.
Habits that help
Scan the whole grid after every big change in the stack. Operations such as perspective, rotation with jitter and the shears affect characters differently depending on their shape, and the grid makes outliers obvious. Punctuation and symbols deserve a look in particular, since they're small and easy to forget until they turn up in a document.
Check figures if the font will be used for anything with numbers: prices on a menu, dates on a poster, page numbers. Filter to Figures and look at them together. Figures that look uneven in width or weight next to each other stand out much more in a table than in a sentence.
Use the Edited filter as a to-do list. When you come back to a project after a break, it's a fast reminder of which letters you've touched and which might need another look.
Why it matters
Every character in a font gets used eventually, usually in the one place you didn't check. The glyphs grid in Font by Zaweba is the simplest way to make sure the whole set looks finished, not just the letters in your favourite test word.