A Background Layer is a parallel layer that sits beside a master layer or a helper layer. Each master and each helper layer can have its own background. It is shown dimmed at 60% opacity in the glyph editor and is read-only — to edit something on a background, swap it onto its host layer first.
A background layer carries:
•An outline of contours and components, any of which can be flagged as a Mask.
•Metrics — sidebearings and advance width — independent of the master.
•Anchors, positioned independently of the master.
•A color and a visibility flag.
Each master row and each helper-layer row in the Masters and Layers panel has its own Background entry. The entry appears the first time something is placed on the corresponding background layer.
View Menu
Three toggles in the View menu control how the background appears in the glyph editor:
•Show Background — toggles whether the background layer is drawn behind the main outline.
•Show Background Nodes — toggles whether the nodes on background contours are drawn. Has no effect when Show Background is off.
•Snap to Background — toggles whether the editor's snapping picks up background geometry as a snap target.
Glyph → Background Submenu
Five commands in the Glyph → Background submenu operate on the background layer:
•Assign Background — adds layers from another open font as the background, useful for tracing a reference design.
•Set as Background (Ctrl+J) — replaces the background layer with the currently selected contours from the master layer.
•Add to Background (Ctrl+Alt+J) — adds the currently selected contours from the master layer to the existing background, leaving the previous background content in place.
•Clear Background (Ctrl+Alt+M) — empties the background layer.
•Swap with Background (Ctrl+M) — exchanges the contents of the master layer and the background layer. Outline, metrics, and anchors are swapped together. The command is its own inverse: running it twice returns the glyph to its original state. Use it to edit something currently on the background.
The same submenu also mirrors the three view toggles described above (Show Background, Show Background Nodes, Snap to Background) for convenient access from a single place.
