Settings (Edit → Settings…)
- Display units — the unit (nm / μm / mm) that coordinates, sizes, and step fields are shown and entered in. Stored values stay nanometer-precise regardless.
- Default path width — applied to new paths on commit. 0 keeps paths hairline.
- Default text size — pre-fills the size field when the Text dialog opens.
- Confirm before destructive actions — ask before "New document" discards unsaved work.
- Invert scroll-wheel zoom direction — flips which scroll direction zooms in.
- Heal imported geometry — the default answer for the close-open-contours-and-heal pass described under Arrange → Close open contours…; on by default. The DWG and SVG import dialogs preset their own checkbox from it, but answer the dialog and it wins for that one file. DXF imports (no dialog) always follow this setting.
Under Advanced:
- Grid density (target px) — the minor grid tries to stay near this pixel spacing as you zoom. Default 12 px; range 4–64. Smaller values give a denser grid.
- Sub-divide grid before it expands past target spacing — when on, a lighter sub-minor grid appears at 1/5 of the minor step whenever the minor step grows much coarser than the target. Keeps snap points visible at all zooms.
- Hierarchy depth — levels of nested cell references drawn in full; deeper instances render as outlines. −1 = unlimited (full fidelity). A big speed-up on dense IP blocks. Also cycled from the status bar (H), and reachable as five menu items under View → Hierarchy (Full / Boxes only / Top level only / One level more / One level less) — the same control without opening Settings. Those five are also what the KLayout keyboard preset's
*/0/1/+/-keys bind to (Keyboard reference appendix, below). - Auto-LOD threshold (px) — references whose on-screen bounding box is smaller than this collapse to a single outline regardless of depth. 0 disables auto-LOD.
- Arc / circle max chord deviation — hard ceiling on how far the flattened arc polyline may fall short of the true arc. Smaller = more vertices = smoother curve. 50 nm is a fab-friendly default.
- Min arc segments per quadrant — floor that prevents tiny circles from collapsing to two-vertex polygons even when the deviation budget would allow it.
(Snap tolerance and snap modes live in the toolbar's Snap settings popover; the polar-tracking angle step is set from the POLAR button in the status bar.)