Layers

Every shape lives on a numbered GDS layer. The Layers panel shows one row per layer:

• Color chip — click to edit color, fill pattern, and mask field tone (see below).
• Eye — toggles visibility. Hidden layers are not selectable.
• Lock — prevents editing shapes on that layer.
• Radio dot — the active layer. New shapes go here, inheriting the active layer's datatype.
• Up / Down chevrons — reorder z-priority within the viewport. You can also drag a layer row by its handle to move it to any position in the list (one undo step).
• Name — editable inline (double-click to rename, Enter to commit, Escape to cancel).
• id/datatype badge — the layer's GDS number and datatype. Double-click to edit the datatype (its "purpose"); new shapes drawn on this layer inherit it.
• Tone badge (DF / CF) — shown when the layer declares a mask field tone: DF (dark field, filled badge) = drawn shapes become chromium; CF (clear field, outlined badge) = drawn shapes become the openings. Set it in the colours dialog. This is app-level metadata that travels with the layer-setup JSON and the document — it records the single most consequential per-mask decision without changing geometry.
• Shape count — the small number to the right of the id/datatype badge is how many shapes are on this layer in the active cell. Layers with zero shapes appear dimmed (KLayout-style "used vs unused" hint), so you can tell at a glance which layers carry geometry without expanding everything.
• Hollow toggle (○ / ◌, hover-revealed) — switches the layer between solid fill and outline-only rendering. Useful when many layers overlap and you want to see edges through one another.
• Opacity slider (hover-revealed, 0–100% in 5% steps) — multiplies the fill alpha for that layer. The stroke is left alone, so even at 0% opacity the layer is still distinguishable by its outline.

Use the + button at the top of the panel to add a new layer.