Font Editor
Linked glyphs and components
Many characters share parts: é is e with an accent, and 好 is 女 beside 子. Draw a part once and link it into every glyph that uses it. A linked layer shows another design inside a glyph, and any change you make to that design reaches every glyph it's linked into.
A glyph can link two kinds of design: another glyph, or a component.
Linking glyphs
Linking one glyph into another is the main way to reuse designs outside Han, and the usual way to build accented letters. Draw the e and the accent once, and every letter built from them follows.
In the glyph's Layers tab, + Linked layer picks a glyph to link, and where to place it. To fine-tune where a linked layer sits, select it and drag it with the Arrow tool, or nudge it with ⇧ and the arrow keys, which leaves the glyph's spacing where it is. The layer moves as a whole and stays linked. When an accented letter isn't drawn yet, the glyph editor offers to build it from its letter and accent: Add all as linked layers.
Components
Some parts aren't characters of their own, such as the water radical 氵 in 河, 海 and 湖. A component is a part drawn for reuse. The Components panel already lists the common components for the module's scripts: select one and add a design with + Blank design. Make any other in the panel's Custom tab: type a character or a name and press New. Or select pixels in a glyph, right-click, and choose Convert to component: it offers the parts this character is made of, so the selection becomes a design of the right component, or a New component....
Drag a design from the Components panel onto a glyph editor to add it as a linked layer.
Designs
A component can have several designs: 氵 drawn narrower for the left of a busy character, say, and wider for a simpler one. When the glyph editor suggests how to build a character, it picks the design of each part that fits where that part goes. Hold ⌥ over a linked layer to try its other designs in place.
Overrides
Drawing on a linked layer changes it in that glyph only; the changes are kept as overrides on top of the link. The layer's menu can then Save as new design, so other glyphs can use the corrected shape, Bake overrides into the component, so every glyph using it gets the change, or Discard overrides.
To cut a layer loose from the design it links, choose Rasterize from the layer's menu.
Building Han characters
Most Han characters are made of smaller ones: 好 is 女 beside 子. When a character isn't drawn yet, the glyph editor suggests building it from the components you have, laid out by the character's structure. It works on half-drawn characters too. Click a suggestion to link its parts, or ⌥-click to add their pixels instead.
Auto-detect components looks through what you've drawn for shapes that repeat, and turns the ones you confirm into components.